£12 POPULAR BRITISH CONCHOLOGY. 



found dead in shelly sand and liviDg in pools between tide- 

 marks, which has the power of entirely withdrawing into its 

 thin, glossy, white, transparent shell; the eyes are always 

 kept nnder the edge of the shell, which protects them with- 

 out interfering with the vision ; in short, the animal, while 

 progressing, can look out of window all the way. 



Y. ToRNATELLA fasciata is a mollusc not usually associ- 

 ated with the Bullida,, and perhaps there are hardly suffi- 

 cient grounds for the union. The shell is oval, with a pro- 

 duced spire, and a fold on the columella; and it has an 

 operculum, which is not the case with any of the other 

 Bullidoi. The animal does not cover the shell ; its head is 

 a squarish disc, divided in front, with two lobed tentacles 

 with eyes at their base. 



When this little milky-white animal is under observation 

 in captivity, it exhibits no timidity, and will not even with- 

 draw its body when approached, but sometimes gives out 

 an opaque whitish fluid tinged with purple. 



YI. Philline, commonly known as Bull^a. The typi- 

 cal and best-known species bears tlie light, transparent, ear- 

 siiaped, open shell, known as B. aperta, which is quite 

 covered by the mantle of the animal. This is thick, white, 

 and slimy : looking down upon it, all that we see is four 



