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



cervical groove, and one between its two branches ; the posterior margin is unarmed, and 

 not specially prominent. 



The chelipedes are wanting in the single specimen. The ambulatory limbs are very 

 similar to those of Eumunida picta, S. I. Smith ; the meri are subsquamose externally, 

 and their anterior margin as well as that of the carpi is fringed with short curved spinules, 

 one of slightly larger size being present on either side of the distal end of the former 

 joints ; the dactyli are flattened and but slightly curved, with a well-marked series of 

 horny spinules present on the posterior margin, a few occurring also on the same margin 

 of the propodi. 



The eyes are of moderate size and the corneae are distinctly rounded. The ischium 

 and merus of the external maxillipedes are subequal, and both are unarmed. 



The abdominal segments are glabrous, and each is crossed by two sparingly pubescent 

 strife. The lateral spines of the second segment are stout and show a tendency to 

 bifurcate. 



This small species in most of its characters closely approaches Eumunida picta, S. I. 

 Smith, from which it may, however, be distinguished at once by the relative size of the 

 hepatic spinules, for in the North Atlantic form these decrease in size from before back- 

 wards, the first being considerably larger than either of the other two. I have dedicated 

 it to the founder of the genus. 



Breadth of carapace (of a male) 5 mm., length of body (including rostrum) 15 mm., 

 of carapace (including rostrum) 9 mm., of rostrum 3 '5 mm., of ambulatory leg (detached) 

 11 '5 mm. 



Habitat. — Station 192, off Little Ki Island; depth, 140 fathoms ; bottom, blue mud. 

 A single specimen. 



Genus Ptychotjaster, A. MUne-Edwards. 



Ptychogaster, A. Milne-Edwards, Bull. Mus. Comp. Zool., vol. viii. No. 1, p. 63, 1880. 



Rostrum slender and spiniform, usually upturned. Carapace narrow and somewhat 

 ovate in shape, with its surface glabrous and usually spinose. Chelipedes and ambulatory 

 limbs slender and greatly elongated, the basal joints of the latter not hidden by the sides 

 of the carapace. Eye-stalks with the corneae dilated. Antennal peduncle slender, the 

 flagellum short. External maxillipedes narrow, the terminal joints elongated. Abdomen 

 folded on itself, the telson (which is transversely segmented) and the last pair of 

 appendages bent under the preceding segments, and applied to the thoracic sterna ; 

 males with the first two pairs of appendages (genital) well developed, those of the third, 

 fourth, and fifth segments rudimentary. Eggs comparatively few in number, and of large 

 size. 



Two species belonging to this interesting deep-water genus have been previously 



