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condition. The genus is compared with Rachitia spinalis, Dana, a young animal taken in the Atlantic, which, however. differs in having the rostrum short, in the first pair of antennæ having only a single flagellum, and in the form of the telson.' The name Oodeopus perhaps alludes to the circumstance that in some of the specimens the feet were beginning to swell or bud out, but for swollen feet the Greeks had already provided the name Edipus, and Dana had already used this name for another genus of prawns, and other naturalists had used it for other purposes before Dana. The alternative derivation of Oodeopus, as meaning 'with feet on the ground,' seems to make the name entirely pointless.

Autonomaa, Risso, 1816, may here be mentioned as a genus of which the position is obscure. It is described as having the first pair of trunk-legs chelate, the second simple. Risso distinguishes it from Alpheus and Nika. Milne-Edwards places it next to Pontonia, Victor Carus puts it between Anchistia and Pandalus. The type species was named Autonomoa Olivii by Risso, but as he makes Cancer glaber, Olivi, a synonym, it is hard to see why it should not be called Autonomoa glaber. Jonathan Couch in his Cornish Fauna is quoted by Adam White and Spence Bate as saying of it: This species has been hitherto unknown as British, but I have examined several specimens taken from the stomachs of fishes, from the depth of fifteen or twenty fathoms. Some of these were of larger size than described from the Mediterranean; one, not the largest, measuring three inches from snout to tail, with antennæ of the length of five inches.'

Legion 4.-Haplopodinea.

All the trunk-legs are similar in structure to each other, simple, six-jointed, with the fifth joint not subdivided, and all but the last pair carry exopods.

Family Hectarthropida.

As this is the only family, its characters are those of the legion. The four genera assigned to it were instituted at the same time as the family and legion.

Procletes, Spence Bate, 1888, meaning 'Challenger,' is represented only by two specimens, the one here de

FIG. 21.-Procletes biangulatus, Sp. Bate [Chall. Rep.].

picted, which is just two-thirds of an inch long, and which is described as Procletes biangulatus, the other Procletes Ellioti, which has a smoother carapace, a shorter flagellum, and a longer telson, being described, it seems, only from a drawing, not from the original specimen taken by the late Sir Walter Elliot, years ago, off the coast of Coromandel.

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Icotopus and Hectarthropus proclaim their adhesion to the family by the meanings of the names, the former signifying with similar feet,' the latter' with six-jointed feet.' The fourth genus which Spence Bate establishes in this family, Eretmocaris, the oar-shrimp,' in allusion to the provision of exopods or swimming-branches, is presumably founded on immature specimens, since it is observed that the first three pairs of appendages in this genus, the eyes and two pairs of antennæ, are attached to a portion of the cephalon projected in front of the carapace, which still retains the embryonic ocellus.' The animals have a very striking appearance from the unusual and

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surprising length of the eye-stalks. This reaches its maximum in Eretmocaris longicaulis (see Plate XIII.), so far as comparative measurements are concerned. The specimen, it is true, is less than a quarter of an inch long, if the eyes are not counted in, but the length is doubled if they are, for these stalked eyes are more than a quarter of an inch long, a proportion between the organ of vision and the rest of the body which probably no other animal in the world can boast of.

In quitting at this point the assistance of Mr. Spence Bate's Report on the Challenger Macrura,' it is right to pay a tribute to the vast labour which that work must have involved, and to the great ability shown in it although amidst many inaccuracies and much want of method. Unfortunately the nomenclature which Mr. Spence Bate adopted makes it sometimes more difficult to read his descriptions than those written in a foreign tongue. He formed the grand conception of giving one invariable name to each part of a crustacean, as it might appear under every possible modification, throughout the whole class. For the comparative anatomist no scheme could be more valuable, but for the students of different orders there is always the chance that such an arrangement will be irritating and repellent. The name that may commend itself as obvious and natural in one group becomes wholly inappropriate in another. Supreme skill might override many difficulties by inventing terms of great simplicity, not inappropriate to any group by being especially appropriate to none. But simplicity seems to have been the very last thing considered in Spence Bate's terminology, and though such words as phymacerite, psalistoma, and stylamblys, may help to curtail the length. of descriptions, they are only too likely also to curtail the number of those that read them.

CHAPTER XVIII

SUB-ORDER III.-SCHIZOPODA

THE mandibles have generally an elongate 'palp.' The second and third maxillipeds are similar in general structure and function to the series of trunk-legs, the whole seven pairs of appendages, and in general the first maxillipeds also, being provided with well-developed exopods or swimming-branches. There are no chelipeds. The ova are carried by the female beneath the trunk, either with or without the protection of marsupial plates, and generally one or two of the larval stages are passed through before the hatching of the young animal. The males are generally distinguished by a special appendage on the first antennæ and by larger pleopods.

The name Schizopoda, cleft-footed,' refers to the double character borne by so many of the appendages, in which the main stem or endopod is more or less ambulatory and the exopod is adapted for swimming. The affinity which the Schizopoda show to some of the Macrura, such as the Pasiphæidæ, and the definite opinion of Mr. Spence Bate that they ought to be included as an aberrant group among the Macrura dendrobranchiata, have been already noticed. Whether they should stand just inside or just outside the sub-order of the Macrura, is a nice point of classification for the learned to decide.

Four families are at present included in the Schizopoda, the Lophogastridæ, Eucopiidæ, Euphausiidæ, and Mysidæ. But on the one hand a suggestion has been made that two forms hitherto assigned to the Mysidae may require the institution of a separate family, and on the other hand Mr. G. M. Thomson, the well-known naturalist of

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Dunedin, New Zealand, has informed me by letter that among specimens which he collected in Tasmania during January, 1892, 'one is especially interesting, a freshwater Schizopod from the very summit of Mount Wellington, that is, from a height of 4,000 feet, and that this crustacean is quite unique, and will require a new family all to itself.' Writing again, he tells me that the animal has no carapace, but is divided like an amphipod, so that he has named the genus Anaspis, which means without a shield.' From the available informatior, therefore, it is not difficult to predict that the number of Schizopod families will in the near future be augmented from four to six.

Family 1.-Lophogastride.

The carapace is rather large, more or less calcareous, loosely covering more or less of the trunk, the segments of which are well defined dorsally. The first maxillipeds are robust, with exopod imperfectly developed or wanting, the epipod very large and projecting within the branchial cavity. The second maxillipeds have the terminal joint obtuse. The six following pairs of appendages are uniform and ambulatory, with well-marked finger. The branchia are arthrobranchiæ, very complex, arborescent, consisting of three or four principal branches, the innermost largest and freely projecting beneath the trunk, and of others covered by the carapace; the hindmost pair are rudimentary or wanting. The marsupium or maternal pouch consists of seven pairs of plates. The pleopods are well developed in both sexes, uniform, natatory. The development is without any free metamorphosis.

G. O. Sars, from whose exceedingly valuable report on the Challenger Schizopods this definition is adapted, allots four genera to this family.

Lophogaster, Michael Sars, 1856, still possesses but a single species, Lophogaster typicus, M. Sars, which at present is only known from the North Atlantic and the South Atlantic, without having been discovered in intermediate positions. It is recorded by Canon Norman from the Shetland Isles. Its sculptured carapace has a short