122 • THE VOYAGE OF H.M.S. CHALLENGER. 



segments arc nearly straight. The first segment of the thorax has a compressed, forwardly 

 directed, curved spine which arises from the middle of the ventral surface of the segments ; 

 there is a trace of a similar pi'ocess on the second segment, which is, however, merely a 

 slight elevation and not a spiny process ; the point at which the thoracic limhs articulate 

 varies in the successive segments ; in the first they arise from a point close to its anterior 

 border; in the second they arise a little further hack, and in the third at about the 

 middle ; the three posterior thoracic appendages arise close to the posterior boundary of 

 their respective segments. 



The abdomen is about as long as the two last segments of the thorax taken together. 

 The first five segments are short and subequal ; the terminal segment is longer and 

 ends in an obtusely pointed extremity. 



The antennules (fig. 2) are about as long as the cephalothorax ; they have the normal 

 structure, the first joint being the longest and stoutest ; the second joint is very short, 

 the third longer. 



The antennas are shorter than the antennules as well as more slender ; the two basal 

 joints are short and subequal, the third joint is long and curved from above downwards ; 

 the flagellum consists of two, one, the distal joint, being very rudimentary. 



The chelipedes are chiefly remarkable for the slenderness of the hand; one of these 

 appendages is shown in fig. 3, where this peculiarity is rendered apparent. 



Of the ambulatory limbs the first pair are rather longer than the two following pairs ; 

 the three anterior pans of thoracic appendages differ from the three posterior pairs in 

 being much more slender. 



The uropoda are biramose ; the basal joint is short and stout ; the outer of the two 

 rami is more slender than the inner, and consists of only one joint, which is furnished at 

 the free extremity with a single long seta; the inner joint is stouter than the outer, and 

 is distinctly Inarticulate; the distal joint, which is shorter than the proximal, bears a tuft 

 of hairs at its extremity. In another specimen both branches of the uropoda are 

 distinctly Inarticulate. 



A single specimen of a species of Typhlotanais was dredged in the North Pacific from 

 a depth of 2050 fathoms in company with the next species Typhlotanais brachyurus; 

 the specimen was mounted on a slide in Canada balsam during the Expedition. I find it 

 impossible to distinguish this individual from those dredged at Kerguelen by any v< v\ 

 distinctly marked characters; at the same time the condition of the specimen does not 

 enable me to speak with great certainty, which is all the more to be regretted, as the 

 occurrence of the same species in very deep and in shallow water is a rare occurrence. 



Station 24G, Mid North Pacific, July 2, 1875; kit. 36° 10' N, long. 178° 0' E.; 

 depth, 2050 fathoms; bottom temperature, 35° - l F.; Globigerina ooze. 



Station 149h, off Cumberland Bay, Kerguelen, January 29, 1874 ; lat. 48° 45' S., 

 long. 69° 14' E.; depth, 127 fathoms; volcanic mud. 



