350 APPENDIX. 



snails with spiral shells ; and a considerable num- 

 ber on the outward coast, which is washed by the 

 ocean. Here are several species of the genera Murex, 

 Fusus, Buccinum, Mitra, Trochus, and Turbo. Fur- 

 ther, there are found here a large Fissurella, and 

 six species of a genus which, from its simple, un- 

 wound shell, would be immediately taken for a 

 Patella ; the creature, however, closely resembles 

 the FissurcUa, with the difference that only one gill 

 is visible in the fissure over the neck. It is re- 

 markable, that on the whole north-west coast of 

 America down to California, no Patella^ only ani- 

 mals of the gQxiMS Acmcea, were to be met with. Of 

 the Chiton genus, six species were observed ; in one, 

 the side skin covers the edges of the shell so far as 

 to leave only a narrow strip of it visible down the 

 back ; in others, the shell is entirely concealed un- 

 der the external skin. It is worthy of remark, that 

 these latter, as well as one similarly formed, found 

 in California, attain the considerable length of eight 

 inches. A third kind, to be reckoned among this 

 subdivision, Pallas obtained from the Kurile Islands, 

 and has described it as Chiton amiculatus. 



Among the Acephala are to be named a large 

 Cardiunif also found on the Californian coast ; Mo- 

 diolus, two species; Mytilus ; Mya, two species; 

 and Teredo pahnnlatus : the latter, which is brought 

 here by the ships, is very mischievous in the har- 

 bour, and attains to the length of two feet. In 

 this species are comprehended three Ascidice, of dif- 



