POLLICIPES POLYMERUS. 315 



and the two lateral margins are also slightly hollowed out ; 

 these are represented in figure 27. The lower segments 

 of the pedicels of some of the cirri, had an additional 

 calcified plate on the anterolateral face. 



These plates are of a faint-brown or yellowish colour, 

 and are conspicuous : the degree of calcification differs 

 considerably; some are quite brittle and very thin, others 

 half horny, and effervesce only slightly in acids. After 

 having been placed in acid, there is no apparent difference 

 between the parts before occupied by the calcified plates 

 and the surrounding membrane; these plates, however, 

 are not superficial, but consist of several of the laminae, 

 which together compose the ordinary integument, in a 

 calcified condition. Like the integuments of the body, 

 and unlike the valves of the capitulum, these calcified 

 plates are thrown off at each exuviation. Neither the 

 exact shape nor number of the plates corresponded in 

 different individuals, nor even on opposite sides of the 

 same individual. The margins of the plates often have 

 a sinuous corroded appearance ; they are, moreover, often 

 penetrated by minute rounded holes, that is, by minute, 

 rounded, non-calcified portions. In one specimen from 

 the Antarctic expedition, there were only here and there 

 a single shield on the segments of the posterior rami, and 

 no plate on the prosoma. Of two specimens in another 

 and older set in the British Museum, from an unknown 

 locality, both had shields on the segments of the cirri, 

 but only one had the large plate on the prosoma. I may 

 here mention that in one specimen, in which the calcified 

 plates were most developed, and which was nearly ready 

 to moult, there were, within the filamentary appendages 

 on the prosoma, small irregular balls of calcareous matter, 

 appearing to me as if calcareous matter had been morbidly 

 excreted, and not like a provision for the future. 



Range. — This species, in the present state of our 

 knowledge, seems to range further than any other of the 

 genus, extending from Upper California, (lat. 32° to 

 35° N.,) across the Pacific, to at least 32° S., perhaps 



