THE APPLE TUN-SHELL. 319 
between the two is, that the Magilus, being a fixed shell and inhabiting a stony tunnel, needs 
not the delicately structured shell required by the active nautilus, and therefore merely fills 
up the useless portions of the shell with solid matter, requiring no hollow chambers and no 
tube of communication. 
THE SporreD NEEDLE-SHELL, or SporreD AUGER, derives its name from the long and 
sharply pointed form of the shell. More than one hundred species of this genus are known, 
all inhabitants of the warmer seas, and the greater part resident within the tropics. In all 
these shells, the aperture is very small and the canal short. The operculum is small and , 
pointed, having the nucleus at the smaller extremity. In many species the animal is entirely 
blind ; and even in those cases where eyes are present, they are very small, and set at the end 
of the minute tentacles. 
The beautiful SporreD IvoRY-SHELL is also a native of the hotter latitudes. 
Few species, not more than eight or nine in number, are known to exist at the present 
day. They are all very smooth and polished on the exterior, and their substance is so thick 
























































































































































































































































































































APPLE TUN-SHELL.—Dolium pomum. 
and solid that they seem almost to be made of earthenware. They reside at a moderate 
depth, being generally found in twelve or fourteen fathoms of water. It is worthy of 
notice that the rich spotted markings of the shell are repeated upon tke body of the animal. 
The members of this genus possess tolerably large eyes, set at the base of the long tentacles. 
As in the preceding genus, the operculum has its nucleus at the pointed end. 
The color of the Spotted Ivory-shell is pure porcelain-white, richly spotted with deep 
brownish-red, something like the tint known to artists as burnt sienna. It is not a very large 
shell, being about two inches in length. 
THE two shells represented in this and in the next illustration belong to the same compre- 
hensive and useful family. The APPLE TUN-SHELL belongs to a moderately strong genus, 
deriving their popular name from the rounded and barrel-shaped outlines of the shell. 
The animal is shown as it appears when crawling, for the purpose of exhibiting the man- 
ner in which the siphon is carried bent over the front of the shell, like the uplifted proboscis 
of an elephant. In these shells the spire is comparatively small and short, and the aperture 
very large, thus producing a great contrast to the needle-shell. The figure in our illustration 
