MUSEUM OF COMPARATIVE ZOOLOGY. 123 



Basal joint of the external antennas armed at the anterior extremity with 

 a slender spine reaching forward as far as do the rostral horns ; movable 

 part of the antenna? exposed from its insertion. An erect spine on the 

 orbital arch. Eye large ; peduncle short. Post-ocular sj)ine reaching be- 

 yond the extremity of the eye. Meros-joint of the external maxillipeds 

 somewhat L-shaped, strongly produced beyond the insertion of the palpus 

 in front and at the postero-interior angle. Feet long and slender. Penult 

 joint of the ambulatory feet of the first pair more than twice as long as the 

 dactyli, and.three times as long as the antepenult joint. 



This genus differs from all the other genera of Collodinae in its interan- 

 tenular spine and the spine on the orbital arch, and especially in the shape 

 of the meros-joint of the external maxillipeds. 



Euprognatha rastellifera nor. sp. 



The following description is that of a male. Carapax naked, with the 

 regions well defined, and minutely and irregulai'ly granulated. There is a 

 single, erect, blunt, almost capitate spine on the gastric, the cardiac, and 

 each branchial region, making four in all, and there are a few smaller 

 spines on the sides of the, branchial, and on the hepatic and pterygosto- 

 mian regions. There is also a small spine on the basal joint of the abdo- 

 men. The interantennular spine projects somewhat beyond the other 

 four spines of the front, which reach to the same vertical plane. The 

 chelipeds are large, nearly twice as long as the carapax ; hand swollen ; 

 fingers not gaping. Ambulatory feet of the first pair nearly one third 

 longer than the chelipeds. The ambulatory feet are naked (except in 

 bearing a few minute curled seta? above), and rough with minute spines. 

 The sternum is regularly granulated, except on the concave portion be- 

 tween the chelipeds. 



Dimensions: Length of carapax, 0.32; breadth, 0.23; length of ambula- 

 tory foot of the first pair, 0.76 inch. 



This crab is an inhabitant of deep water, ranging from 80 to 138 fathoms, 

 and occurred in considerable abundance, as follows : — 



Off the Samboes, May 9. 



Off Alligator Reef, May 8, 1869. 



Off Sand Key, * May 16, 1868. 



Off the Samboes, May 9, 1868. 



S. W. of Sand Key, February 17, 1869. 



Off Boca Grande, February 15, 1869. 



Off Sand Key, May 11, 1868. 



S. W. of Sand Key, February 17, 1869. Cast No. 3. 138 " 



Cast No. 



5. 



80 fathoms. 



Cast No. 



6. 



88 



Cast No. 



2. 



120 " 



Cast No. 



12. 



123 " 



Cast No. 



2. 



125 " 



Cast No. 



5. 



125 " 



Cast No. 



11. 



128 " 



