LAMELLARIA. 47 



to the south. Its name is Sigaretus debilis, Sig-a- 

 re'-tus deb'-i-lis. It is pure white, very flat, and has 

 a small spire but a very large aperture. Its breadth 

 is about an inch. 



Somewhat resembling this last shell, but smaller, 

 is the one shown in Fig. 27, named Lamellaria 

 Steamsii, Dall, Lam-el-la'-d-a Sterns'-i-i. 

 It is pure white, very thin, and has so large an 

 aperture that the interior of the shell is plainly 

 Fig. 27. v j s jbi e< jt s breadth is about half an inch. 

 In this species, as well as in the next one to be de- 

 scribed, the thin shell is wholly concealed by the large 

 development of the mantle. 



The little Velvet Shell is represented in Fig. 

 28. It belongs to the same species that lives on the 

 coast of Great Britain, and its name is Velutina 

 Icevigata, Linn., Vel-u-ti'-na lev-i-ga'-ta. You will 

 notice that it is one of the few of our species which 

 received its name from the great Swedish naturalist, 

 Linne, and the reason for this fact is obvious. As 

 shown in the figure, the spire is short, the 

 outer lip thin, and the aperture large and 

 nearly circular. The color is light brown, 

 Fig. 28. an ^ the size is about that of a pea. It derives 

 its name from the velvet-like epidermis which, 

 in fresh specimens, covers the shell. It is a northern 

 species, and is found along the shores of Puget Sound 

 and the adjacent regions. 



Triforis adversa, Mont., Trif-o-ris ad-ver'-sa, is a 

 little mollusk, having a minute, spire-shaped, many- 

 whorled shell, the surface of which is reticulated or 

 netted, and the aperture of which is small. 



There is one peculiarity about this shell which 

 makes it differ from any of those which we have 



