POLLICIPES MITELLA. 317 



Maxillae, deeply notched : caudal appendages, multi- 

 articulated : filamentary appendages, none. 



Philippine Archipelago, Mus. Cuming : China Sea, Mus. Brit. : Amboyna 

 and East Indian Archipelago, according to Rumphius and other authors : 

 Madagascar, according to J. E. Gray. 



Capitulum, compressed, consisting of the scuta, terga, 

 carina, rostrum, and a large pair of upper latera, with a 

 single lower whorl of smaller valves ; these latter vary 

 from 22 in very small specimens, to 26 in large speci- 

 mens. The capitulum, therefore, is formed of at most 

 34 valves ; but in the largest specimen seen by me, the 

 capitulum being 2*3 of an inch in width, there were only 

 32 valves. In the smallest, namely, with a capitulum 

 "15 of an inch in width, there were 30 valves. The valves 

 are remarkably strong, and formed of white shelly matter ; 

 they are closely approximate, and overlap each other : the 

 scuta and terga are articulated together by a fold ; the 

 apices of the valves are either worn and disintegrated, or 

 they project freely like horns beyond the sack, to a much 

 greater extent than in any other recent species of the 

 genus : even a considerable portion of the scuta projects 

 obliquely upwards. The exterior surfaces of the valves 

 (when not worn) are covered by a strong yellow mem- 

 brane, and the upper free parts are generally attached 

 together for some little length by this same membrane. 

 The valves are plainly marked by the zones of successive 

 growth ; and most of them are ribbed and furrowed 

 slightly, from their umbones to their basal margins. The 

 yellow external membrane, examined microscopically, is 

 marked by, or rather formed of, numerous growth-lines, 

 crossed by longitudinal beaded ridges. The tubuli are not 

 numerous, and of small diameter. 



Scuta (PI. VII, fig. 3 a , a) triangular, with the apex 

 more or less produced, according to the state of its pre- 

 servation, and a little curved towards the terga ; basal 

 margin, and in some degree the tergo-lateral margin, 

 arched, and slightly protuberant; occludent margin thick- 



