REVIVAL OF AN EARLIER VIEW

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ferred. The Anomoura are not distinguished from the Brachyura and Macroura by any common character; from the former they differ by the disposition of the vulvæ, from the latter by not having a fan-shaped termination to the pleon. But all the organs vary extremely in the Anomoura, and no bond of connexion between the Apterura and Pterygura is found either in the shape of the antennæ, mouth, maxillipeds, trunk, plastron, branchiæ, or in that of the pleon. The Anomoura contain forms which differ more from one another, than the Brachyura do from the Macroura. By the Anomoura the closest relationships are torn asunder, as the Dromiacea from the Maiacea, the Raninoidea from the Leucosiæ, the Porcellanidea from the Galatheæ, the Megalopidea from the Astacoidea.'

This criticism, published in 1841, appears now to be winning deserved acceptance. The recent researches of M. F. Mocquard into the armature of the stomach also show the Anomura to be an artificial division. With the transfer of the Pterygura to the Macruran sub-order, in which all the families are pterygurous, the name becomes inappropriate and may give place to the older name. Anomala, used by Latreille, though in a narrower application. Any slight inconvenience that may result from the similarity of name between the Brachyura anomala and Macrura anomala will be compensated by the reminder thus supplied that these two tribes correspond with the collective Anomura of Milne-Edwards.

The Macrura contain the following tribes:-Anomala, Thalassinidea, Scyllaridea, Astacidea, Stenopidea, Penæidea, Caridea, among which will be found along with others those popularly well known as Hermit Crabs, Lobsters, Crayfishes, Prawns, and Shrimps.

The following Table shows the subdivision of the tribes into legions and families :—

MACRURA ANOMALA

TRIBE I.-ANOMALA.

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The pterygostomian regions are free from the epistome and marked off from the back by a suture or continuous furrow. The fifth pair of legs are generally weak, not fit either for walking, swimming, or grasping food and prey. The tribe embraces five legions, Hippinea, Lithodinea, Pagurinea, Porcellaninea, Galatheinea.

Legion 1.-Hippinea.

The carapace is ovate or subquadrate, comparatively smooth, the regions ill defined, the front' broad. The corneæ of the eyes are small. The first antennæ are in general strongly developed, with one flagellum elongate, the other of moderate size or absent. The second antennæ have usually a short flagellum and a massive peduncle of four or five joints, with or without a movable acicle on the second. The third maxillipeds are moderately broad, sub-operculiform. The walking-legs have a flattened terminal joint. The fifth pair are slender and filiform and folded under the preceding pair. The sterna of the trunk are linear. The pleon is partially extended, with the telson large, longer than broad, and the preceding segment carrying a pair of biramous lamellar appendages, not so arranged as to form a rhipidura. The males have no appendages to the pleon but those of the penultimate segment.

The members of this legion inhabit the shallow waters of tropical and subtropical seas. They are divided between the two families of the Hippida and Albuneidæ.

Family 1.-Hippida.

The third maxillipeds are sub-operculiform, with a broad fourth joint; the exopod is wanting. The first pair of legs are sub-cylindrical and not chelate. The telson is elongate, lanceolate.

This family includes three genera.

Hippa, Fabricius, 1793, has been much restricted since it was first instituted. It is now especially distinguished

from its companions by the large and long flagellum of the second antennæ. Hippa emeritus (Linn.) is regarded by Mr. J. E. Ives as a very variable species widely distributed on the east and west coasts of North and South America. It is used, he says, by the fishermen for bait, and large numbers are dug from the sand. It is not unlikely, as suggested by Milne-Edwards, that Hippa talpoida, Say, the 'mole-like' Hippa, is the same species. It was upon this that Professor S. I. Smith made his observations at the United States' Biological Station at Wood's Hole, Massachusetts, in the summer of 1875. He was there able to obtain a nearly complete series of the postembryonal stages, and has since elaborately described the second, third, and last zoëa forms, and the succeeding megalopa condition. Some of his figures are reproduced on Plate IV. He observed that the adults preferred a very narrow zone of the shore, at or very near low-water mark, where they lived gregariously, burrowing in the loose and changing sands.

The smooth, oval form of the animal,' he says, ' with the peculiar structure of the short and stout second, third, and fourth pairs of thoracic legs, enables them to burrow with far greater rapidity than any other crustacean I have observed. Like many other sand-dwelling crustaceans, they burrow only backwards; and the wedge-shaped posterior extremity of the animal, formed by the abrupt bend in the abdomen, adapts them admirably for movement in this direction. When thrown upon the wet beach, they push themselves backward with the burrowing thoracic legs, and by digging with the appendages of the sixth segment of the abdomen slightly into the surface, direct the posterior extremity of the body downward into the sand.'

The second antennæ are generally held between the second and third maxillipeds, with the peduncles crossed in front, and the flagella curved down and entirely round the mouth so that the setæ with which they are densely armed all project inward. Their function is not unreasonably supposed to be that of removing objectionable

particles from the other appendages within their reach. For this brushing service they must be well adapted, since in ordinary adult specimens there are from a hundred to a hundred and fifty joints in the flagellum, and from eight to twelve setæ to each joint. Most of these setæ are only slightly bent, but armed on the outside of the curve with a great number of variously shaped teeth. On either side of each bundle, however, there is a very long seta, convolutely curved inward at the extremity, and along nearly its whole length densely furnished with long, slender, secondary setæ, arranged in a double series on the inner side of the curve. Already in the megalopa stage, Professor Smith found that the mandibles had become thin and foliaceous and completely consolidated with the walls of the oral opening. This extremely unusual condition of those organs persists in the adult, and seems to have perplexed the few naturalists who have earlier examined them. It must be a subject of surprise that a crustacean of such a family as this should be able to dispense with the biting power usually so strongly developed in the mandibles. But we are told that in all specimens examined the alimentary canal was filled with fine sand, and as the material from the stomach showed under the microscope a small quantity of vegetable matter, the inference is not improbable that, much after the fashion of the earthworm, the creature obtains nutriment from the sand which it passes through its body. Milne-Edwards was evidently under the impression that the true second segment of the pleon in this genus was its first segment, but Professor Smith has shown very clearly that the first pleon-segment is in the adult coalesced with the trunk, a thing very unusual but none the less in this case quite to be depended on.

Remipes, Latreille, 1806, has the peduncle of the second antennæ large, but the flagellum quite small. The first segment of the pleon is free, the telson lanceolate, of great length. As in Hippa, the female carries appendages on the second, third, fourth, and sixth segments of the pleon. The founder of the genus and several writers since have supposed the first pleon-segment to be the last segment of