27S SCALPELLUM V1LL0SUM 



Affinities. — In the downward growth of all the valves, 

 in the presence of a sub-rostrum, in the shape of the 

 scuta, carina, and more especially of the triangular latera, 

 in the form of the peduncle, with its irregularly- scattered 

 calcified scales, in the shape of the animal's body, in the 

 structure both of the mandibles and maxillae, in the 

 arrangement of the spines, both on the anterior and pos- 

 terior cirri, Scalpettum villosum most closely resembles, or 

 rather is identical with, Pollicipes. Had it not been for 

 the fewness of the valves forming thecapitulum, and from 

 the presence of Complemental Males, I should have placed 

 this species alongside of Pollicipes spinosus and sertus. 

 In not having caudal appendages, 8. villosum differs from 

 all the species of Scalpellum and Pollicipes ; but this 

 organ is variable to an unusual degree in Pollicipes. 



COMPLEMENTAL MALE. PL VI, fig. 4. 



From the kindness of Professor Owen, Mr. Gray, and 

 Mr. Cuming, I have been enabled to examine six speci- 

 mens of this species ; and on two of them I found Comple- 

 mental males. They were attached in the same position 

 as in 8. Peronii ; namely, beneath the adductor muscle, 

 in the fold between the scuta, so as to be protected by 

 the latter when closed. This parasite is six-valved, and has 

 a close general resemblance with that of S. Peronii, but 

 differs in very many points of detail. It is represented 

 of the natural size at a fig. 4. The capitulum is ^ths 

 of an inch, measured across the scuta and terga ; and 

 the same measured from the base of the carina to the top 

 of the capitulum ; hence it is broader, by a quarter of the 

 above measurement, and considerably higher than the 

 male of S. Pero7iii. From the capitulum being higher, 

 that is, not so much truncated, the orifice is placed more 

 obliquely. The membrane connecting the valves is 

 finely villose, and is besides furnished with spines, con- 

 spicuously thicker and longer than those on the male 

 S. Peronii. The scuta and terga are much more elongated, 



