the animals either occur in groups, as in the genus Balanus, or the intromittent organ is extremely long, as in Acasta, thus enabling one individual to fertilize another. Anelasma squalicola always occurs in pairs in the skin of sharks. But in the two genera, Ibla and Scalpellum, the individuals are either solitary or, if in clusters, are so crowded and twisted that the apertures of the capitulum are distant from each other.

The case of a simple separation of the sexes would not strike us as being peculiar; but an instance where a hermaphrodite, with fully developed testes, vasa deferentia, and intromittent organ, besides female organs, has within its shell from one to ten complemental males can, I think, be explained only on the ground of adaptation for cross-fertilization.

(FIG. 8) MALE OF S. REGIUM ENLARGED. (From W. Thompson.)

The eggs pass from the ovaries and are borne for some time inside the capitulum. They undergo a total segmentation of the yolk and hatch a Nauplius, a free swimming form with mouth, stomach, and intestine, a triangular carapace with two prominent frontal horns and a posterior spine, beneath which is seen the forked abdomen. (Figure 9, Nauplius of Balanus balanoides? from a

(FIG. 9.) YOUNG OF THE BALANUS, ENLARGED.

MS. drawing by Dr. Packard.) They have three pairs of swimming feet, the first simple, the posterior two biramose, and all three terminating in long bristles. They soon change to a pupa form (Figure 10, pupa of Lepas australis; a, an tennæ; c, cirri; m, mouth; from Darwin), which has the triangular shield of the Nauplius folded together in a bivalve form; the six pairs of thoracic limbs are present, and also the antennæ. After

swimming about for a while the animal attaches itself by its antennæ, as shown in the figure, and undergoes a metamorphosis by which the eye becomes internal, the antennæ are concealed by the growth of the peduncle, the valves of the capitulum are formed,

and, in a word, the animal attains its adult retrograde condition.

Barnacles first appeared in the upper Silurian age. At the present day they are found in every sea, and the various species are widely distributed. Some are attached to piles and rocks; Acasta is found in sponges, Lepas fascicularis forms of its cement a float by which it is supported, Coronula is found in the skin of whales; Anelasma squalicola, as its name indicates, inhabits the skin of sharks; Chelonobia is found on the backs of turtles in the tropical seas. There is an interesting specimen in the Museum of the Peabody Academy of Science at Salem, Mass., of Conchoderma aurita which had attached itself to a Lernean Crustacean (Penella), which in turn was parasitic upon the large sunfish (Orthagoriscus mola).

The anatomy of the Cirripeds has been worked out by Burmeister, St. Ange, and Darwin. The figure of the nervous system given by St. Ange is wonderfully imperfect. It has, however, been copied by Coldstream in Todd's Cyclopædia of Anatomy, in Owen's Lectures on Invertebrate Anatomy, and Carus Icones Zoötomie. Their embryology has been studied by Thompson, Burmeister, Darwin, and Fritz Müller, while a systematic account of the subclass is given by Darwin in two volumes published by the Ray Society, to which the reader is referred for further particulars concerning this interesting group.

RECENT LITERATURE.

THE ZOOLOGY OF WHEELER'S SURVEY.' Since the spring of 1871, Lieutenant Wheeler has been conducting an examination of the biology of the Western Territories, which his parties have traversed, in connection with his geographical and geological explorations. No connected reports upon the facts and material obtained by the survey have ever been published, however, and our knowledge of them has been limited, with one or two exceptions, to brief accounts of discoveries read to scientific societies. The publication of this splendid volume of zoological results is therefore an event in the history of this survey, one which is calculated to increase its friends, — and a monument to the perseverance and skillful zeal of the field naturalists.

The report contains over one thousand quarto pages, and is made in the name of Dr. H. C. Yarrow, who, until recently, was naturalist-incharge of the survey; but he acknowledges assistance in the prepara

1 Reports upon the Zoological Collections obtained from Portions of Nevada, Utah, California, Colorado, New Mexico, and Arizona, during the Years 1871-74. Explorations and Surveys west of the One Hundredth Meridian. Lieut. Geo. M. Wheeler in charge. Volume V. Washington. 1875. 4to, pp. 1020.

tion of special features from a large corps of well-known scientific men. The opening paper treats of the geographical distribution of the animal life of the West, as shown by Lieutenant Wheeler's explorations. This is followed by the account of the mammals observed, written by Dr. Elliott Coues and Dr. Yarrow, which goes extensively into the synonomy of the species mentioned, and gives copious notes upon habits, etc. Although the collections were large there were no novelties, and hence no plates accompany this paper. Chapter III., Ornithology, is by Mr. H. W. Henshaw, and is illustrated by fifteen plates of new species or varieties of birds. They are drawn by Robert Ridgway, and well drawn, but the chromo-lithographic process of coloring has failed to give a worthy effect in several cases, and some of the plates look cheap. The text of the Ornithology is full of news, and great praise belongs to Mr. Henshaw for his active and careful observance of the manners and songs of the little-known birds of the Southwest. This is the most entertaining and the longest chapter in the volume. Dr. Yarrow himself writes the report upon the Batrachians and Reptiles, of which a large series of great value was secured, and unites with Prof. E. D. Cope in describing the fishes, which have been somewhat neglected by Western expeditions heretofore. Both of these papers are accompanied by many finely engraved plates, partially colored; and both are preceded by a discussion of general characteristics. The collections of Hymenoptera are reported upon by E. T. Cresson and Edward Norton; the Diurnal Lepidoptera, by Theodore L. Mead and W. H. Edwards; new species of Zyganida and Bombycida, by Richard H. Stretch; the Diptera, by Baron OstenSacken; the Coleoptera, by Henry Ulke; the Hemiptera, by Professor Uhler; the Orthoptera, by Professor Thomas; and the Neuroptera, by Dr. Hagen. Dr. Yarrow, with quite unnecessary apologies as to unfitness, presents the report upon the Mollusks, showing that even the more barren plains of New Mexico and Utah support many species of terrestrial and fluviatile mollusks, as well as the mountain meadows of the more Northern Territories; and extending almost or quite across the continent, the range of some of our common Eastern species. The final chapter is by Professor Verrill upon fresh-water leeches. This last half of the book, also, is adorned with a large number of plates finely drawn and exquisitely colored.

Perhaps the

WEISMANN'S FINAL CAUSES OF TRANSMUTATION.1 most remarkable biological work of the year is Prof. August Weismann's treatise on the Final Causes of Transmutation, forming the second part of his Studies on the Theory of Descent. The first part of the work, entitled Seasonal Dimorphism, appeared in 1875. The present work is divided into four divisions, of which the first presents a striking array of

1 Studien zur Descendenz-Theorie. II. Ueber die letzten Ursachen der Transmutationen. Von Prof. AUGUST WEISMANN. Mit fünf Farbendrucktafeln. Leipzig. 1876. 8vo, pp. 336.

facts on the origin of the markings of caterpillars. The author describes the nature and morphology of the markings of larvæ of the family Sphingidæ, their biological value and tribal development, concluding that the oldest Sphingid caterpillars were without markings; that the oldest style of markings were longitudinal lines, the later ones oblique streaks, and the last to be developed, the spots. This part of the subject is illustrated by five colored plates. In the third section the transformation of the Mexican axolotl into an Amblystoma is discussed at considerable length, and with characteristic thoroughness. Professor Weismann believes that the Siredon or axolotl was originally derived from a land salamander (Amblystoma), but has reverted to an axolotl, or larval form, through the change of the climate of Mexico from a damp to an exceedingly dry one, obliging these animals, which as larvæ, lived in ponds, and as adults lived under fallen trees and stones or in damp places, to revert to the original larval Siredon form and remain permanently amphibious. In the fourth division, on the mechanical conception of nature, the author maintains that development is mechanical, and that we must reject the idea of a special life-force. Still he as strongly believes in teleology, and maintains the thesis that evolutional views do not tend to materialism.

GLOVER'S ILLUSTRATIONS OF INSECTS.1 This is a large quarto volume, containing ten excellent copper-plates illustrating the leading types of plant-bugs (Hemiptera not including the Homoptera), with 132 pages of text, a fac-simile of the author's own handwriting, printed on prepared lithographic paper. The letterpress contains useful lists of predaceous or parasitic bugs (Heteroptera), of the vegetable or animal substances destroyed by them, and of remedies against their attacks used or suggested by various writers. The value of the work is greatly increased by the aid of Mr. P. R. Uhler, "who has materially assisted in preparing the work by furnishing the specimens from which to figure, for advice and correcting the text, for the classification and valuable notes." The edition consists of but fifty or sixty copies for private distribution, and is a storehouse of useful information for agriculturists, which we wish could be more widely published.

LOVEN'S STUDIES ON THE ECHINOIDS.2. This elaborate memoir presents matter of special interest to the paleontologist as well as to the zoologist and anatomist. Chiefly zoological in its character, the text and plates are mostly devoted to a discussion of the homologies of the shell of the sea-urchins, particularly those forms related to extinct genera of echinoids. Comparisons are also instituted with the classes of 1 Manuscript Notes from my Journal, or Illustrations of Insects, Native and Foreign. Order Hemiptera, Suborder Heteroptera, or Plant-Bugs. By TOWNSENnd Glover. Washington, D. C. 1876. 4to, pp. 132.

2 Etudes sur les Echinoides. Par S. LOVEN. (Kongl Svenska Vetenskaps- Academiens Handlingar. Bandet II., No. 7.) Text and Atlas of 53 Plates. Stockholm. 1875. 4to, pp. 91.

Asteroids (star-fish) and Crinoids, which will, if we mistake not, be found of much use to palæontologists. Especial attention is devoted to certain organs called Spherides, grouped around the mouth of sea-urchins, for the discovery of which naturalists are indebted to Professor Lovén.

But to our mind the most interesting portion of the work is the exquisite drawings illustrating the anatomy and distribution of the nervous system and the water system of vessels. We have here for the first time, clearly shown, the more intimate relations of these organs.

The plates are abundant and beautifully executed, the lithographs rivaling in clearness and delicacy the best steel engravings.

MACALISTER'S ANIMAL MORPHOLOGY.'- Though this book was written in 1873, it is still the most recent manual of animal morphology in the English language, and will be found by advanced teachers to be very useful. The system of classification is that of Haeckel as modified by Huxley, and is based on recent embryological studies. The sponges are regarded as belonging to a distinct subkingdom, Polystomata of Huxley. The Labyrinthulee of Cienkowsky are admitted as a class of Protozoa. The Mollusca are regarded by the author, and we think correctly, as "only an extreme of specialization" of Vermes; in another place (page 241), "Their structure can be easily understood by regarding them as Vermes with no articulated appendages, modified by unequal lateral development, and by a fusion of metameres." For convenience they are regarded as a subkingdom. The Tunicates are placed among the Vermes in accordance with Gegenbaur's classification. The Polyzoa are placed among the Vermes, while rather inconsistently (probably because Gegenbaur first did so) the Brachiopoda are retained among the Mollusca. The volume ends with the Insects; a second volume, containing the Vertebrates, has just been issued from the press. Had we space to

be critical we should feel inclined to find some fault with the author's classification of the Arthropoda, which he does not, however, claim to be original.

RECENT BOOKS AND PAMPHLETS. Report on the Transportation Route along the Wisconsin and Fox Rivers, in the State of Wisconsin, between the Mississippi River and Lake Michigan. By Gen. G. K. Warren. Washington. 1876. 8vo, pp. 114. With Ten Maps.

The Grotto Geyser of the Yellowstone National Park. With a Descriptive Note and Map, and an Illustration by the Albert-type Process. (U. S. Geological and Geographical Survey of the Territories, F. V. Hayden, U. S. Geologist-in-Charge.) Washington, D. C. Folio.

The History of Spontaneous Generation. By Edward S. Dunster, M. D. (From Transactions of the Ann Arbor Scientific Association. Vol. i. 1871.) Ann Arbor. 8vo, pp. 30.

Über Dimorphismus und Variation einiger Schmetterlinge Nord Amerikas. Briefliche Mittheilung von J. Boll in Texas. 1876. 4to, pp. 3.

1 An Introduction to Animal Morphology and Systematic Zoology. By ALEXANDER MACALISTER, Professor of Comparative Anatomy and Zoology, University of Dublin. Part I. Invertebrata. London: Longmans, Green, & Co. 1876. 12mo, pp. 461. With a few Cuts.