EEPOE.T ON THE ANOMURA. 171 



described, viz., Ptycliogaster spinifer, A. Milne-Edwards, takeu by the "'Blake" at 

 seven stations in the West Indies, at depths varying from 123 to 183 fathoms, and 

 Ptycliogaster formosus, A. Milne-Edwards, dredged by the " Talisman " off the Canaries, 

 at the great depth of 4000 metres (2187 fathoms). The Challenger dredgings have added 

 two new and interesting forms to the list. 



Ptycliogaster milne-edwardsi, Henderson (PI. XX. fig. 2). 



Ptychogaster milne-edwardsi, Henderson, Narr. ChalL Exp., vol. i. p. 900, fig. 330, 1885 ; Ami. 



and Mag. Nat. Hist., ser. 5, vol. xvi. p. 418, 1885. 



Cliaracters. — The carapace is narrow in front though widening out poisteriorly, with 

 its surface glabrous and covered by slender acute spines, which attain their largest size 

 towards the middle line. The gastric area is moderately convex, and is armed with a lateral 

 and two submedian pairs of spines, as well as with two unpaired spines which are situated 

 in the middle line ; the cardiac area is circumscribed and remarkably convex, with a pair 

 of prominent spines placed in front of three smaller spinules ; at each antero-lateral angle of 

 the cardiac area there is a small convex elevation surmounted by a spine of large size. The 

 spines on the branchial regions are of small size, and closely grouped together ; there are, 

 however, two submedian pairs placed behind the cardiac area which attain a considerable 

 size. The rostrum is narrow, acute, and strongly upturned, with its length equal to more 

 than one-third that of the carapace. The lateral margin of the carapace bears three 

 almost equidistant spines on its anterior half, the first of which is placed at the antero- 

 lateral angle, while the posterior half is armed with a number of closely set spinules ; the 

 epimeral suture is very distinct and situated a little below the lateral margin ; the 

 branchiostegite has considerable vertical extent and its surface is spinulose. The posterior 

 margin of the carapace is slightly raised, and bears a number of minute spinules. 



The chelipedes are narrow, subcylindrical, and of great length, with the joints uni- 

 formly covered by short slightly curved spinules, which are arranged in six or seven 

 distinct rows on each joint ; the right chelipede is considerably shorter than the left, 

 a result perhaps due to accident. The carpus and palm are subequal in length, but 

 both are exceeded by the merus ; the fingers are nearly two-thirds the length of the 

 palm, and are slightly curved, they are subcylindrical in shape, and gradually taper 

 towards the pointed apices, while their opposed margins are densely setose and armed 

 with conical teeth, which gradually decrease in size from behind forwards, and two of 

 which near the proximal end of the fingers are considerably larger than the others. The 

 ambulatory limbs are slender, subcylindrical, and greatly elongated, with the joints armed 

 in a similar way to the chelipedes ; the dactyli are short and flattened, being only about 

 one-fourth the length of the propodi, and a series of long horny spines is present on their 

 posterior margin. 



