TI :A. 



The under surface of a large line yellow specimen is represented in 

 Tint. \ i |, 1. 



Moot of tin- specimen* which 1 have seen are grey. A small one is 

 .-hewn, fig. '2, upper MII lUce ; 6g. 3, under surface ; fig. 4, tcntacuhim and 

 . enlarged. 



Grey specimens attain nearly the dimensions of tin- \ el low ones. 

 1 have been unable to discover any important distinctions between 

 them. If the syphon of some has appeared long, the body triangular, 

 and the cloak expanding irregularly, it might be owing to the emae 

 state of the individuals, or other causes. However, the cloak, owing to 

 its colour, is more transparent than that of yellow specimens. A thin 

 slough is cast off the upper surface. Fig. 5, upper surface ; fig. 6, under 

 surface. 



Under the cloak is a pure, thin, beautiful shell, of a very peculiar 

 form. In real structure it s> approach three rotates, the first per- 



forated, the last very wide and flattened. A grey specimen having died. 

 I committed it to a vessel of sea-water with a prawn, in hopes that the 

 animal would be consumed, and the shell left en tin-. This plan succeeded. 

 The same was done with another of an orange colour, which is not repre- 

 sented here. 



In the Sigaretus it is the cloak which, by its projection, forms a 

 snout.* In the Trilonium vndalum, theCypraea, and others, it is the lle-h 

 of the animal folded. 



The creature is partly pelagic, partly littoral. It is not common. 



PLATE V. 



FIG. 5. Shell, back. 



6. The same, face. 



7. Shell of fig. 6, back. 



8. The same, orifice. 



The reader will profit by consulting Curier, Sur let Molliuquet, fat the anatomy of 

 the Sigarrhu; also Montagu, in I.inntrnn Transaction*, vol. xi. p. 186; and the observa- 

 tions of Dr George Johnston, in London Magazine of Natural History, vol. ix. p. 229. 



