POLLICIPES SPINOSUS. 325 



Capitulum, flattened, triangular, broad, with the valves 

 varying in number, in full-grown specimens of the same 

 size, from 30 to above 60 ; the scuta, terga, and carina 

 are very much larger than the other valves ; the rostrum, 

 however, is nearly half the size of the carina ; the remaining 

 valves are exceedingly small. In some specimens there is 

 only one whorl under the carina ; in other specimens there 

 are distinctly two whorls. The scuta, terga, and carina 

 stand pretty close together ; they are moderately thick, 

 and are covered, in chief part, by yellowish-brown mem- 

 brane, which is destitute of spines. 



Scuta, triangular, broad, basal margin slightly pro- 

 tuberant. 



Terga, as large as the scuta, flat, regularly oval, basal 

 point blunt and rounded. 



Carina very slightly curved, triangular, internally 

 rather deeply concave, basal margin straight. The inner 

 and growing surface is four fifths of the entire length of 

 the valve. In half-grown specimens the apex projects a 

 little outwards. 



Nostrum, small, much curled inwards ; the basal margin 

 is much hollowed out ; the inner surface is broadly tri- 

 angular, more than twice as wide as high, and about 

 one fourth of the entire length of the valve. The re- 

 maining valves, about 26 in number, do not correspond 

 on the opposite sides of the same individual, they are 

 exceedingly small, with the sub-carina, sub-rostrum, and 

 three pairs of latera a trifle larger than the lower latera, 

 which are generally arranged in two whorls. In shape 

 all the latera are nearly alike ; they consist of flattened 

 styles, with their inner surfaces transversely oval, and more 

 or less elongated, the larger ones being most elongated. 



Peduncle, broad, barely as long as the capitulum. The 

 calcareous scales are irregularly shaped, minute, elongated 

 and pointed, placed in separate transverse rows, and 

 crowded together in each row. Only the scales in the 

 uppermost row grow regularly; but some of the lower 

 scales continue to be added to irregularly, and hence are 



