314 POLLICIPES POLYMERUS. 



Generative System. — Both ovaria and testes are largely 

 developed ; the former fill the long peduncle ; the testes 

 enter both the pedicels of the cirri, and the filamentary 

 appendages on the prosoma; vesiculse seminales very large, 

 reflected at their ends, extending across each side of the 

 stomach. Penis rather small, coloured purplish, with nu- 

 merous little tufts of bristles. 



Variation. — In some specimens in the British Museum, 

 collected by Sir J. Ross, in the Southern ocean, and in 

 another older set from an unknown source, several parts 

 of the outer tunic of the animal's body presented the 

 remarkable fact of being calcified, but to a variable 

 degree ; whereas in several specimens from California, 

 there was no vestige of this encasement. Considering 

 it most improbable that the calcification of the integu- 

 ments should be a variable character, I most carefully 

 compared the above-mentioned sets of specimens, valve 

 by valve, tropin by trophi, and cirri by cirri, and found no 

 other difference of any kind ; therefore I cannot hesitate to 

 consider both to be the same species. The first Southern 

 specimen which I examined presented the following cha- 

 racters : on the prosoma there was a central longitudinal 

 band, formed of a thin, brittle, brown-coloured calcified 

 layer, which became irregularly rather narrow towards the 

 thorax; on each side it sent out six or seven irregular 

 rectangular plates, which surrounded and supported the 

 bases of the two rows of filamentary appendages; and out- 

 side these, some of the papilliform projections also had their 

 bases surrounded by small, calcified, separate rings. The 

 thoracic segments corresponding with the second, fourth, 

 fifth, and sixth cirri had, on each side, an elongated cal- 

 cified plate ; on the ventral surface of the thorax, between 

 the first and second cirri, there were two minute plates. 

 In all the cirri, excepting the first pair, the segments of 

 the rami, and in the three posterior pairs, the segments 

 of the pedicels, had their dorsal surfaces strengthened 

 by oblong, quadrilateral, calcified shields, the upper mar- 

 gins of which are notched for the dorsal tufts of spine, 



