178 THE VOYAGE OF H.M.S. CHALLENGEE. 



which at the distal end of both joints become distinct spines. The propodus is slightly 

 swollen in both its diameters and its surface is perfectly smooth ; the fingers are 

 more than half the length of the palm and their surface is pubescent, the apices are 

 curved, the dactylus folding under the immobile finger, and a single tooth is present on 

 the inner margin of each. The ambulatory limbs are of moderate width, and with the 

 exception of a row of minute spinules on the anterior border of the meri (and in some 

 cases also of the carpi) are smooth, a series of distinct horny spinules also occurs on the 

 posterior margin of the propodi ; the dactyli are more than half the length of the 

 propodi and strongly curved, with from six to eight stout horny spinules articulated to 

 the posterior margin of each, the apical one being of small size. 



The eyes are of small size, with the cornese subglobose and deeply pigmented. The 

 antennal acicle is long and acuminate, extending slightly beyond the end of the 

 peduncle, the last joint of which is prolonged inferiorly into an acute spine, and its basal 

 portion is rather broad ; the flagellum is remarkably short, not reaching the end of the 

 rostrum, and consisting of scarcely half a dozen joints. The external maxillipedes are 

 almost completely smooth, one or two minute spinules being found only at the distal 

 end of the merus. 



The abdominal segments are smooth and glabrous externally, with the pleura sub- 

 acute, those of the third segment and the posterior part of the second segment being- 

 narrow and attenuated. The telson and last pair of appendages are of very small size. 



This small species is distinguished by the form of its rostrum, and the armature of 

 the chelipedes, as well as by the remarkable characters of the external antennae. 



Breadth of carapace of the largest specimen (a female with ova) G mm., length of 

 body (including rostrum) 16 mm., of carapace (including rostrum) 9 mm., of chelipede 

 20 mm., of chela 9 mm., of first ambulatory leg 12 mm., diameter of ova about 0'8 mm. 

 Males are of somewhat smaller size than the above (as are also the other females with 

 ova) but their chelipedes are considerably stouter. 



Habitat. — Station 310, Sarmiento Channel, Patagonia; depth, 400 fathoms; bottom, 

 blue mud. About thirty specimens, including both males and females, several of the 

 latter with ova. 



Uroptychus politus, Henderson (PI. VI. fig. 2). 



Diptychus polihis, Henderson, Ann. and Mag. Nat. Hist., ser. 5, vol xvi. p. 420, 1885. 



Characters. — The carapace is moderately convex from side to side, and everywhere 

 perfectly smooth and glabrous, the margins even being entire, with the exception of a 

 minute denticle at the antero-lateral border. The rostrum is horizontal and placed very 

 slightly below the level of the highest part of the carapace, in length it exceeds the eye- 

 stalks by a small part of its extent, and it narrows somewhat abruptly towards the apex. 



