320 POLLICIPES MITELLA. 



corresponding with a slight external central ridge, formed 

 as heretofore by the overlapping of two of the valves of 

 the lower whorl. Basal margin nearly on a level with that 

 of the scnta and with the basal points of the terga. 

 The foregoing eight larger valves form the main cavity, 

 in which the body of the animal is lodged. 



Valves of the Lower Whorl. — These, seen externally, 

 seem to belong to more than one whorl, but inter- 

 nally their basal margins stand on a level. They vary in 

 number, as already stated, from 22 to 26. I have seen 

 an individual with a valve more on one side than on the 

 other. They are of unequal sizes, but they are rather 

 variable in this respect : the largest are not above half the 

 size of the upper latera : three or four pairs, together with 

 the sub-rostrum (e) and sub-carina (c), are always larger 

 than the others : these two latter valves differ from the 

 others only in being more concave. Seen externally, all 

 these valves project considerably, and curl a little inwards, 

 with their apices generally worn and truncated. Viewed 

 internally (fig. 3 b'), whilst the valves are in their proper 

 places, the inner and growing surfaces of the smallest are 

 seen to be triangular, — of the larger, some are rhomboidal, 

 and others quadrilateral with the upper side much longer 

 than the lower. These latter valves overlap the upper 

 parts of the little valves on both sides of them ; the rhom- 

 boidal valves overlap a valve on one side, and are over- 

 lapped on the other ; the triangular valves are overlapped 

 on both sides. 



The corium lining the capitulum is produced into 

 narrow purple crests, which enter the interstices between 

 the valves, more especially along the line separating the 

 upper and lower whorls. There is, also, a distinct flattened, 

 tapering, free projection of corium, which enters between 

 the carina and sub-carina ; and another between the ros- 

 trum and sub-rostrum. 



Peduncle, much compressed, short, rarely as long as 

 the capitulum ; in one very large specimen it was ex- 

 tremely short, barely one fifth of the length of the capi- 



