2 
THE VOYAGE OF H.M.S. CHALLENGER. 
OXYRHYNCHA or MAIOIDEA. 
Oxyrhynchi, Latreille (pt.), Hist. Nat. Crust., vol. vi. p. 85, 1803. 
Oxyrhinques, Milne Edwards, Hist. Nat. Crust., vol. i. pp. 263, 266, 1834. 
Canceriens Cryptopodes, Milne Edwards, tom. cit., pp. 368, 369, 1834. 
Maioidea vel Oxyrhyncha, Dana, U.S. Expl. Exped., vol. xiii. Crust. 1, pp. 66, 
75, 1852. 
Oxyrhyncha, Miers, Cat. New Zeal. Crust., p. 2, 1876; Journ. Linn. Soc. Lond. 
(Zool.), vol. xiv. p. 634, 1879. 
Carapace more or less narrowed in front, and usually rostrated ; with the branchial 
regions considerably developed. Hepatic regions small. Epistome usually large. 
Buccal cavity quadrate, with the anterior margin straight. Branchiae nine in number ; 
their efferent channels terminating at the sides of the endostome or palate. Antennules 
longitudinally plicated. The carpal joint of the endognath of the exterior maxillipedes 
is articulated at the summit or at the antero-internal angle of the merus. The verges of 
the male are inserted at the bases of the fifth ambulatory legs. 
The Oxyrhyncha, thus defined, constitute as a whole a very natural group ; which 
however is connected with the Cyclometopa by almost insensible gradations, and no 
single character can be mentioned which will suffice to distinguish them universally from 
the other Brachyura. 
Legion I. MAIINEA. 
Maiinea, Dana, U.S. Expl. Exped., vol. xiii., Crust, i. pp. 76, 77, 1852. 
„ Miers, Journ. Linn. Soc. Lond. (Zool.), vol. xiv. p. 640, 1879. 
Basal antennal joint well developed, inserted beneath the eyes, and usually occupying 
a great part of the infraocular space. 
Family I. Inachida 
Inachidai, Miers, Journ. Linn. Soc. Lond. (Zool)., vol. xiv. pp. 640-642, 1879. 
Eyes non-re tractile, or retractile against the sides of the carapace. Usually the orbits 
are not defined, but there is often a well-developed prseocular and postocular spine. 
Basal joint of the antennse generally slender, sometimes moderately enlarged. 
The carapace varies in shape, being subtriangulate or oblong-triangulate or subpyri- 
form, rarely suborbiculate. Rostrum simple or bifid, sometimes very short. Chelipedes 
