521 



variety has fometimes five, one of which is extremely 

 fmall and linear : thefe fub-volutions are defined by a 

 deprefTion, and are wrinkled tranfverfely : aperture com- 

 prefled, femi-lunar. Diameter one tenth of an inch. 



This is fo variable in its formation, that without great 

 attention, it might be formed into feveral fpecies. 



We have found it plentiful on all the fandy fhores we 

 have examined ; the fined and largeft on the coafts of 

 Devonjldre and Cornwall. It frequently happens, that 

 the interior part is worn, and becomes pervious ; in 

 which ftate Mr. Walker has figured it; for we cannot 

 confider it any other than his fhell ; and we are the more 

 confirmed in this opinion, by the fpecimens favoured us 

 by Mr. Boys from the coaft o^ Sandivich for it, none of 

 which were perforated. 



If this is the 5. Seminulum o^ Oue.li'h , of which there 

 is very little doubt, it is found in the Adriatic and Red-' 

 Seas ; and fometimes in a foffilc ftate. 



6. 

 Serpula fubrotunda dorfo elevato. JValk. Min. Shells, f. A. SuBROxuNDyji. 



V. with a fub-orbicular, fub-compreffed, fmooth, 

 gloffy, opaque, white fhell ; compofed of three com- 

 partments, the middle one elevated above the others on 

 the upper fide ; not vifible beneath : aperture fmall, 



X X X angulated; 



