MUSEUM OF COMPARATIVE ZOOLOGY. 121 



The ambulatory feet of the second pair are rather longer than those of 

 the first pair. The dactyli of the ambulatory feet are armed with spines 

 along the inner edge. 



The dimensions of the single specimen found, a male, are as follows : 

 Length of carapax, 0.24 ; breadth, 0.18 ; length of ambulatory foot of the 

 first j>air, 0.45 inch. 



Off Carysfort Reef, March 21, 1869. Cast No. 7. 40 fathoms. 



Arachnopsis nov. gen. 



Carapax oblong, narrow, and somewhat truncated in front. Rostrum short, 

 bifid. Orbital arch high, protuberant. Postocular spine long, and separated 

 from the orbital arch by a deep, narrow fissure. Eye long, considerably 

 overreaching the tip of the postocular spine, but capable of being drawn 

 back beneath it. Basal joint of the external antenna? with a small, sharp 

 spine at the extremity, pointing obliquely forward and outward, between 

 which and the rostrum the movable part of the antenna is exposed, and 

 with a spinulous crest on the inferior surface extending back to the angle 

 of the buccal area. Meros-joint of the external maxillipeds broader than 

 long, and with sharply prominent external and internal anterior angles. 

 Ambulatory feet long, filiform ; those of the second pair longest ; dactyli 

 straight, acute, and nearly as long as the penult joint. 

 f This genus differs from Collodes in its filiform ambulatory feet and long 

 eye peduncles. 



Arachnopsis filipes nov. sp. 



Body armed above with three erect, slender, blunt spines, one on the 

 gastric region, one on the cardiac region, and one on the basal joint of the 

 abdomen. Abdominal spine small ; cardiac and gastric spines equal and 

 about as long as the distance between the orbital arches. Carapax convex 

 anteriorly, and flattened posteriorly. Surface of carapax smooth and 

 glossy, naked, except for a few hairs on the anterior part of the bran- 

 chial, the sides of the gastric, and the frontal region. Beneath, the sub- 

 hepatic and pterygostomian regions are armed with spiniform granules. 

 Chelipeds in the male as long as the carapax and much curved ; edges 

 of meros and carpus spinulose ; hand nearly smooth ; fingers as long as the 

 palm. Ambulatory feet spinulose along the lower edges of all the joints, 

 except the dactyli ; those of the second pair more than twice as long as 

 the carapax. Sternum, abdomen, and external maxillipeds tuberculated. 



Dimensions of a male : Length of carapax, 0.25 ; breadth, 0.18 ; length 

 of ambulatory foot of first pair, 0.5 inch. 



Off Conch Reef, May 11, 1869. Cast No. 2. 34 fathoms. 

 Off Carysfort Reef, March 21, 1869. Cast No. 7. 40 " 

 Off Trench Reef, March 21, 1869. Cast No. 2. 45 " 



