REPORT ON THE ANOMURA. 17 



Genus Hypoconcha, Guerin-Meneville. 



Hypoconclia, Gu^rin-M^neville, Rev. et Mag. Zool., s(5r. 2, No. 6, p. 333, 1854. 

 „ Stimpson, Proc. Acad. Nat. Sci. Philad., p. G4, 1858. 



Carapace flattened, membranous above ; the anterior border arcuate and sharply 

 defined, overhanging a triangular frontal region the apex of which is directed downwards. 

 External maxillipedes with the meral joints large, and the external-lateral angles of the 

 latter somewhat produced ; the exognath robust. The ultimate and penultimate pairs 

 of ambulatory limbs furnished with Y-shaped dactyli. Sternal sulci in the female 

 widely separate, each terminating in a tubercle opposite the basal joint of the second 

 ambulatory leg. 



The members of this genus are, so far as is known at present, confined to the West 

 Indies and the neighbouring shores of America. The protection which so many Dromiids 

 obtain from an Ascidian or Sponge, is in the present case afi"orded by the detached valve 

 of a Lamellibranch, and the Hypoconcha is able to closely adjust the chelipedes and 

 ambulatory legs to the under surface of its body. The genus Conchoecetes, established 

 by Stimpson for the Cancer artificiosa of Herbst — a native of the Chinese seas, — also 

 possesses this peculiar habit, as well as an Australian species, Dromia conchifera, 

 Has well. 



Hypoconcha sahulosa (Herbst). 



Faux Bernard THermite, Nicholson, Essai sur I'Hist. Nat. de Saint-Domingue, p. 338, pi. vi. 



figs. 3, 4, 1776. 

 Cancer sahulosus, Herbst, Naturg. Krabben u. Kjebse, tab. xlviii. tigs. 2, 3, 1796. 

 Faux Bernard I'Hermite de Nicholson, Lamarck, Hist. anim. sans vert, t. v. p. 264, 1818. 

 Hypocoiicha sabulosa, Gu(Srin-M(5nevLlle, Rev. et Mag. Zool., s(5r. 2, No. 6, pi. v. p. 333, 1854. 

 ,, „ Stimpson, Proc. Acad. Nat. Sci. Philad., p. 64, 1858. 



Habitat. — St. Thomas, West Indies ; shallow water. 



Two adult specimens in the collection — a male and a female, the latter bearing ova- 

 agree with Guerin-Meneville's description and figure.^ The last two abdominal segments 

 in the female are, however, slightly granulated, a character which Stimpson assigns to 

 his species Hypoconcha arcuata, originally taken at St. Thomas. 



1 It is to be noted that in this author's plate, figures 1 and 5 represent two very different configurations of the 

 anterior border of the carapace. The Challenger specimens agree with the first of these, in which the border is well 

 rounded off and only a very slight concavity exists on either side. 



(zool. CHALL. EXP. — PART Lxix. — 1887.) Zzz 3 



