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



Tanais hirsutus, F. E. Beddard (PI. XVI. fig. 9). 



Tanais hirsutus, F. E. Beddard, Froc. Zool. Soc. Lond., 188G, pi i. p. 11G. 



This species is represented by a considerable number of specimens dredged off Prince 

 Edward Island, in 50 to 150 fathoms. 



The length of the largest specimen is about 9 mm. 



The body is elongated, the anterior region is wide, the posterior thoracic segments 

 narrower ; the last thoracic segment and the first three abdominal segments are again 

 wider, after which the body narrows towards the termination. 



The head and first segment of the thorax form a quadrangularly shaped piece; the 

 anterior margin is notched on either side of the short obtuse rostrum for the articulation 

 of the antennae ; external to the articulation of the latter are the ocular lobes, which are 

 somewhat projecting and rounded ; eyes are present and well developed ; the antero-latcral 

 angle of the cephalothorax is formed by a rounded projection to the outside of the 

 ocular lobes ; behind this the lateral margins of the cephalothorax arc almost straight, 

 only slightly divergent, the posterior region of the head being wider posteriorly than 

 anteriorly ; the dorsal surface of the cephalothorax is convex and swollen. The two 

 first free segments of the thorax are short and subequal, and about as wide as the 

 cephalothorax ; the third segment is narrower but longer, about as long as the first two 

 taken together ; the two following segments increase progressively in length ; the first of 

 these is about twice the length of the preceding segment, their diameter is a trifle less 

 than that of the preceding segment The last thoracic segment is wider than tin- 

 preceding but a little shorter ; the first three segments of the abdomen are wider as well 

 as longer than the following ; they are subequal to each other in length and only a little 

 shorter than the last segment of the thorax ; the first abdominal segment is rather wider 

 than the last segment of the thorax, the second wider still, the third shorter again ; the 

 two following segments are very short as well as narrow ; the terminal segment of the 

 body ends in a blunt rounded extremity. 



The first pair of antennse consist of three principal joints; the basal joint is the longest 

 and stoutest, the second is shorter and more slender ; the third joint is longer than the 

 second but more slender ; the palp is represented by two or three minute joints ; the 

 distal extremities of the joints of the peduncle are surrounded by a dense circle of fine 

 hairs, plumose, and of great length. 



The second pair of antennse resemble the first almost entirely in structure but are 

 rather shorter ; the rudimentary flagellum appears to be absent ; they are densely beset 

 with fine hairs. The cutting edge of the mandibles is furnished with two teeth, the 

 molar processes are strongly developed and stouter than the extremity of the mandible ; 

 the palp is absent. 



The clielse are stout and strong ; the next three thoracic limbs are subsimilar, and 



