210 THE VOYAGE OF H.M.S. CHALLENGER. 



The first pair of pleopoda in the female is biarticulate, uni-branched and foliaceous ; 

 the second biramose and foliaceous, carrying no stylamblys ; outer plates of the rhipidura 

 without a diaeresis. Telson long and tapering. 



This genus is very closely related to Spongicola in most of its anatomical details. 



The eyes and the first and second pairs of antennae are of the same generic value. 

 The scaphocerite in Spongicola is of moderate length, relatively broad at the base, and 

 somewhat tapering towards the extremity, but not ending in an acute point, while in 

 Stenopus it is long, with the margins subparallel. The mandible and first two pairs of 

 siagnopoda are simdar in the two genera, but the third has one more joint to the limb 

 proper in Stenopus than in Spongicola. The two pairs of gnathopoda are also 

 generically of the same value respectively as those of Spongicola. The form of the first 

 pair is almost identical in the two genera. The second pair differs in relative length, 

 and the basecphysis in Stenopus is short, slender, uniarticulate, and feeble, while in 

 Spongicola it is short, two-jointed, and robust ; so rudimentary that it escaped the 

 observation of de Haan and other carcinologists, who state that it is wanting. 



The pereiopoda are mostly of the same generic value, and support a similar branchial 

 arrangement. In both genera the third pair of pereiopoda is the largest, in Stenopus 

 it is long and slender, in Spongicola it is long, but the propodos is very broad, and the 

 carpos short ; the posterior two pairs are not multiarticulate, and terminate in a 

 triunguiculate dactylos, whereas in Stenopus they are multiarticulate and terminate in a 

 biunguiculate dactylos. 



The pleopoda are also of the same generic value, and the telson is long and tapering 

 almost to a point, whereas in Spongicola it terminates in a rounded or obtuse extremity. 



In general character Stenopus is long, slender, and spinous. In Spongicola the 

 animal is shorter, more robust and smooth. But, with the exception of the spinous 

 condition of Stenopus, the feature that chiefly influences the general appearance is 

 the shortness of the carpos, and the great thickness of the projaodos in the third pair 

 of pereiopoda of Spongicola when compared with the same in Stenopus. 



Geographical Distribution. — It has been chiefly recorded from the eastern seas and 

 the shores of India by Desmarest, Milne-Edwards, and Sir Walter Eliott ; from Japan 

 by de Haan ; from the " Coral Eeef of Raraka, one of the Paumotu Islands ; also 

 Balabac Passage north of Borneo," by Dana, who has determined a second but some- 

 what less spinous species (Stenopus ensiferus) from the Fiji Islands ; while the 

 Challenger brought home one specimen from the Fiji Islands, as well as one from 

 Bermuda; and, according to Risso, a species, Stenopus spinosus, has been taken in the 

 Mediterranean Sea. Milne-Edwards 1 says, "Squilla groenlanclica of Seba, which Herbst 

 calls Cancer astacus longipes, and placed by Olivier in the genus Palsemon, appears to 

 be a mutilated specimen of this species (Stenopus hispidus), of which the two large feet 



: Hist. Nat. des Crust., vol. ii. p. 407. 



