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



projection occurs at the distal inferior end of the propodi, to which from eight to ten 

 horny spines are articulated ; the dactyli are short and strongly curved, with nine or ten 

 spinules gradually increasing in size towards the apex, present on the inferior margin. 



The eyes are of small size, and partially concealed in orbits, -with the cornese not 

 dilated. The antennal acicle is elongated, being more than twice the length of the eye- 

 stalks, and extending almost to the end of the antennal peduncle. A few ill-defined 

 spinules occur on the inner margin and at the distal end of the merus of the external 

 maxillipedes. 



The abdominal segments are smooth and glabrous externally, with their pleura 

 subacute ; the pleuron of the second segment is bilobed, a feature common to most 

 members of the genus, and the rounded anterior lobe overlaps the postero-external angle 

 of the carapace. 



This fine species is distinguished by the armature of its carapace, chelipedes, and 

 ambulatory limbs, and the small size of its eyes. With the exception of Uroptychus 

 nitidus (A. Milne-Edwards), it is the largest known species belonging to the genus. 



Breadth of carapace (of an adult male) 12 "4 mm., length of body (including rostrum) 

 34 mm., of carapace (including rostrum) 17 '5 mm., of ehelipede 45 mm., of chela 

 19 '5 mm., of first ambulatory leg 29 mm. Females appear to equal the males in size, 

 but their chelipedes are more slender ; the ova have a diameter of nearly 1 mm. 



Habitat. — Station 145a, ofi" Prince Edward Island; depth, 310 fathoms; bottom, 

 volcanic sand. Two males, four females (one bearing ova), and several young specimens. 



Uroptychus spinimarginatus, Henderson (PL XXL fig. 2). 



Diptychus spinimarginatus, Henderson, Ann. and Mag. Nafc. Hist., ser. 5, vol. xvi. p. 419, 1885. 



Characters. — The carapace is glabrous, though its surface is roughened posteriorly 

 and towards the lateral margins by very minute granulations, and in some specimens also 

 the same parts are pubescent ; no spines are met with anywhere on the surface. The 

 rostrum is about four times the length of the eye-stalks, and three-fourths that of the 

 remainder of the carapace ; it is horizontal in direction, its lower surface bears a median 

 carina, and two or three minute spinules are present on each lateral margin towards the 

 apex. The posterior half of the lateral border of the carapace is armed with five large 

 and prominent spines, the first of which reaches a larger size than any of the others, the 

 second and third being subequal, as are also the fourth and fifth ; the anterior half bears 

 three or four spines of small size, including that at the antero-lateral angle. The ptery- 

 gostomial region terminates anteriorly in a short acute spine. 



The chelipedes are elongated and extremely slender, with the proximal joints finely 

 tubercular and armed with a few short spines. A spine is placed at the upper distal end 

 of the basis, a second at the lower distal end of the ischium, and two on the inner distal 



