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



The first free segment has well-developed epimera, prolonged anteriorly into a spine ; 

 the three last segments of the thorax have also epimera, which are prolonged into a 

 short spine; in these segments, however, the spine is directed backwards instead of 

 forwards as in the first segment ; the intermediate segments have short epimera without 

 any spines ; upon all the free thoracic segments, with the exception of the first, are a 

 pair of longish lateral spines, situated between the articulation of the limbs and the 

 anterior margin of the segment. These have been also described as existing in some of 

 the segments, at least, of Typhlapseudes, but in the present species they are present 

 upon all and very much longer. 



The length of the abdomen is rather less than one-half of the length of the entire 

 body ; the first five segments are subequal in length and do not appear to decrease in 

 breadth, or, if they do so, it is imperceptibly ; the postero-lateral regions are more 

 prolonged outwards than in the last species, and the spines overlying the articulation of 

 the limbs are better developed than in Typhlapseudes. The terminal segment of the 

 abdomen is longer than the last three taken together ; it is cylindrical in form, with 

 straight lateral margins ; it is somewhat widened out posteriorly. 



On the ventral surface of all the thoracic and abdominal segments, with the excep- 

 tion of the last, is a median spine situated rather nearer to the anterior than to the 

 posterior margin of the segment. I have already referred to the presence of a similar 

 series of spines in Typhlapseudes, but in that genus they are almost confined to the 

 thoracic segments, being extremely minute upon the abdomen. 



The antennules are rather long, measuring about as much as the cephalothorax and 

 first two free thoracic segments taken together. 



The first joint of the peduncle is the longest and stoutest, it is slightly curved lik<* an 

 S ; the three remaining joints of the peduncle decrease gradually in size ; there are two 

 flagella, of which the inner is very much shorter, as well as more slender than the outer 

 fiagellum ; it consists of about six elongated joints. The outer flagellum is longer than 

 the peduncle ; it is made up of very numerous joints — I counted twenty-seven in one 

 specimen — which are longer but more slender distally. 



The antennee (PI. XV. fig. 6) are hardly so long as the first joint of the peduncle of 

 the antennules. The peduncle is about equal in length to the fiagellum ; the first joint 

 is short and stout and has a longish projection on the inner side ; the second joint is 

 much more slender but longer; on the outer side it is prolonged beyond the articulation 

 of the succeeding joint, and on this prolongation is placed the movable exopodite, which 

 is distinctly three-jointed, the basal joint being much longer than the two distal joints; 

 the third joint of the peduncle is extremely short, the two following joints are long and 

 subequal ; the fiagellum is composed of about four slender joints. 



The mandibles. — One of these appendages is shown in fig. 1 of PI. XII. ; the extremity 

 is divided into two slightly divergent processes which are of a dark brown colour, and 



