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



of 700 fathoms; the other from the same locality but from deeper water (1100 

 fathoms). These specimens only differ from each other in colour ; the larger specimen 

 (from 1100 fathoms) is of a pale buff colour; the smaller of a rich brown, they are 

 both males. The larger specimen measures about 7 mm., the smaller about 5 mm. in 

 length. 



The general shape of the body is much like that in the genus Munna; it is covered 

 everywhere with innumerable short slender spines which are of varying size, but nowhere 

 attain any great length ; the majority are branched, and the appearance of these spines 

 reminds one very strongly of the spicules of many sponges. A number of the spines 

 from the thorax as well as the abdominal shield are figured on PI. XII. figs. 8, 8a, 86, so 

 that their characteristic form can be seen. 



The head is narrower than the following first thoracic segment ; it has a pair of 

 lateral eyes placed a little way behind the articulation of the antennae, and elevated on 

 stalks like those of Munna. The thoracic segments gradually increase in width up to 

 the third ; the diameter of the fourth segment is equal to that of the third ; the remaining 

 segments gradually diminish ; the general outline of the thorax is therefore oval ; the 

 first three segments of the thorax are concave forwards, the fourth is straight and forms 

 the transition to the three posterior segments of the thorax which are concave backwards. 

 The antero-posterior diameter of the first four thoracic segments is subequal, the fifth 

 is of about half the length of the fourth ; the remaining segments gradually diminish, 

 the spines are not scattered irregularly over the surface of the thorax, but are chiefly 

 condensed upon two ridges which traverse the dorsal region of the segment from side to 

 side. On the last three segments of the thorax the spines are confined to the lateral 

 regions of the segments, the dorsal region being perfectly smooth and apparently without 

 a trace of spines. 



The epimera are small. 



Between the last segment of the thorax and the abdominal shield is a single free 

 abdominal segment. The abdominal shield is spiny, like the anterior region of the 

 thorax, a row of rather long spines marking the lateral margin. The abdominal shield 

 is very convex down to where the uropoda articulate ; behind this it suddenly becomes 

 flattened and smooth and terminates in a truncated somewhat excavated posterior 

 margin. The uropoda are articulated just between the posterior and the anterior 

 regions of the caudal shield, apparently on the dorsal surface ; the large size of the 

 socket of articulation of these appendages would seem to indicate that they themselves 

 are of considerable size, and perhaps not so rudimentary as is usual in the genera 

 belonging to this family. The anterior region of the caudal shield is divided by furrows 

 into a median and two lateral convexities. 



The antennules (PI. XII. fig. 9) have a four-jointed peduncle and a long flagellum ; the 

 first joint of the peduncle is short and rounded, the second joint is equally short but more 



