DESCRIPTIONS OF THE GENERA AND SPECIES. 
BRACHYURA, 
Cancri Brachyuri, Lamarck (pt.), Syst. des Anim. sans Vert., p. 148, 1801. 
Brachyures, Milne Edwards, Hist. Nat. Crust., i. p. 247 (1834). 
Brachyura, Leacli (pt.), Trans. Linn. Soc. Lond., vol. xi. p. 307, 1815. 
,, Latreille (pt.), Fam. Nat. du Regne Anim., p. 267, 1825. 
,, Dana, U. S. Expl. Exped., vol. xiii. Crust. 1, p. 58, 1852. 
,, Miers, Cat. New Zeal. Crust., p. 1, 1876. 
„ Claus (pt.), Grundziige der Zoologie, ed. 4, vol. i. p. 632, 1880. 
,, Haswell, Cat. Australian Stalk and Sessile-Eyed Crust., p. 1, 1882. 
The cervical and thoracic regions of the body are covered by the carapace, which is 
greatly developed. The antennulary fossettes and orbits are usually well defined. 
The buccal cavity is distinctly defined in front. The sternum is never linear, the vulvse 
are situated upon the sternum. The post-abdomen, in the male, is short ; indexed 
beneath the cephalothorax, and usually closely applied to it. The flagella of the 
antennules and antennae are usually short or rudimentary. The exterior maxillipedes are 
operculiform and usually completely close the buccal cavity. The anterior legs are 
developed as perfectly chelate limbs (chelipedes). The ambulatory legs (i.e., those of 
the second to the fifth pairs) are never perfectly chelate ; but rarely, in those forms which 
establish the passage to the Anomura (e.g., the Dorippidse) are feeble and imperfectly 
prehensile. 
The Brachyura, or short-tailed, i.e . , true crabs, are, as stated in the introductory 
portion of this Report, here limited in the sense long ago indicated by Profs. H. Milne 
Edwards and J. D. Dana ; who may perhaps still be regarded as the leading authorities 
on the systematic classification of the Crustacea; and are subdivided into the four 
secondary divisions or subtribes, Oxyrhyncha, Cyclometopa, Catometopa, and Oxystomata. 
The recent species, as is well known, are extremely numerous, for the most part 
marine, and inhabitants of the shores or shallower waters of the temperate, subtropical, 
or tropical regions of the globe; but few species occurring in the Arctic or Antarctic 
circumpolar areas of distribution. Others (Geocarcinidse, Thelphusidse) are terrestrial or 
fluviatile, and a few (Pinnotheridse) inhabit the shells, &c., of animals of other groups. 
Until recently, little was known of the bathymetrical distribution of these animals, but 
the Challenger and other recent expeditions have shown that species, especially of the 
somewhat aberrant family Dorippidse, may occur in the abysses of the ocean to a depth 
exceeding 1500 fathoms. 
(ZOOL. CHALL. EXP. — PART XLIX. — 1886 .) 
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