145 



have numerous hairs disposed on the surface, the more distal segments having hairs almost 

 exclusively roand the base of each following segment. 



The second cirrus also has very unequal rami : the short ramus has 7 segments and 

 looks as if it was truncated at the extremity; the long one has 20 segments, increasing slightly 

 in length, but decreasing considerably in breadth towards the extremity of the ramus. Shorter 

 ramus and lower 6 — 7 segments of the longer ramus thickly clothed with hairs. 



The third cirrus has shorter rami tha'n the 4"' — 6 th cirri. Surface of the lower 10 

 seo-ments densely clothed with hairs in both rami. Number of segments 16 in the shorter, 18 

 in the longer ramus. 



The fourth-sixth cirri have slightly longer rami — but even these cannot be said 

 to be very long. The number of segments seems to increase from the 3 ld to the 6 th : at 

 least I found in a specimen the following numbers: 



3 ld cirrus ... 16 and 18 segments 



4 th cirrus ... 19 and 20 segments 



5 th cirrus ... 22 and 22 segments 



6 lh cirrus . . . 23 and 24 segments. 



All the segments of the 4 th — 6 th cirri bear at the anterior side two pairs of stronger 

 and a third pair of delicate bristles; at the posterior side near the extremity of each segment 

 a few delicate spines, which on the more distal segments are almost rudimentary. 



The eau dal appendage is very slender; I counted 25 segments in one of them. 

 Length of last segments (PI. XIII, fig. 13) about four times their breadth. 



The penis is thick, broad at its base, tapering towards the extremity. It is distinctly 

 ringed and bears delicate hairs scattered over its surface; at and near the extremity, the hairs 

 are disposed much more densely. 



This species was collected at : 



Stat. 74. June 8, 1899. Lat. 5 3'. 5 S., Long. ii9°o'E. Depth 450 m. Bottom: Globigerina 



ooze (obviously a thin layer). Numerous specimens attached to the spines of 



Cidaris (Histocidaris) elegans Alex. Agassiz. 

 Stat. 267. December 20, 1899. Lat. 5°54'S., Long. I32°56'.7E. Depth 984111. Bottom: grey 



mud with a brown upper layer. Six specimens, two of them attached to a spine 



of Cidaris misakiensis Yoshiwara, the others loose ; the latter have also been 



attached to a cylindrical object. 

 Stat. 297. January 27, 1900. Lat. io°39'S., Long. i23°4o'E. Depth 520 m. Bottom: soft 



grey mud with brown upper layer. One specimen attached to a spine of Cidaris 



japonica Döderlein. 



General Rem ark s. This is a very peculiar species of Verruca. It shows some 

 resemblance to V. radiata Gruvel in the structure of the moveable valves, although the articular 

 ridges of the scutum, which in V. radiata are very narrow, are quite broad in V. grex. 

 The shape of the fixed valves and of the rostrum and carina especially, is quite different from 

 what we find in other species of the genus. 



The number of specimens on the same spine of a Cidaris is sometimes considerable. 



17 



SIBOGA-EXPEDITIE XXXI a. 19 



