: GASTEROPODS 367 
strate its ability to hide itself completely within its house and to 
close the door very effectively by means of its operculum. The 
eyes seem to be wanting, or they are concealed under the skin 
of the head. The shell is usually quite large, with a depressed 
spire and well-rounded whorls—especially the body-whorl, which 
appears to be greatly swollen. The umbilicus is usually open and 
moderately large, the lip simple. 
Genus Polynices (Lunatia, Natica). 
P. heros: (generally referred to as Lunatia or Natica heros). One 
of the commonest large shells and one of the most characteristic species 
of the New England and New Jersey littoral fauna. It is exceedingly 
common along the Long Island shore, where it may be found on the 
open beach, in pools witha sandy bottom left by the receding tide. It is 
usually partially and frequently wholly buried in the sand. The umbili- 
cus is open and large, the operculum corneous, and the shell heavy and 
ashy-white to brownish, with (when young) a yellowish epidermis. Its 
length is from two to four inches. It has no ornamentation whatever. P. 
heros is a most voracious creature and spends its time in hunting for 
flesh — either alive or dead —to devour. It feeds upon dead fish, or 
upon other mollusks whose shell it is able to pierce by means of its 
radula, making a little round hole through which it sucks out the flesh 
from within. The curious egg-cases of this species have already been 
referred to. (See Plate I.) It glues together particles of sand into the 
form of a basin with the bottom knocked out and broken on one side. 
In the gelatinous substance of this basin it deposits its eggs in a regular 
order. These hatch out in midsummer. Egg-cases of this kind can 
always be found wherever Polynices lives. For a long time naturalists 
were greatly puzzled by these curious things, and their blunders are 
recorded in earlier works, where these egg-cases have been elaborately 
described as living animals belonging to various invertebrate orders. 
The largest and best specimens of P. heros are to be found south of 
Cape Cod. (Page 343.) 
P. triseriata. A small shell of exactly the same shape as P. heros, 
but decorated with three revolving series of bluish or chestnut spots. 
It is pretty well determined that this so-called 
species is only the young of P. heros. It is very 
abundant all along the coast. 
P. duplicata. This is even more abundant 
than P. heros. Ithasa flatter shell, with an obtuse 
apex and dome-like spire. The umbilicus is 
partly or wholly closed by a thick, callous, shelly 
process thrown off from the columellar lip, and is _Potynices triseriata, young ; 
chestnut in color. The surface of the shell is lutte: Wseriata, older 
smooth, often polished, ashy-white below and light 
chestnut above. The operculum is corneous. The length of the shell 
varies in different localities from one half of an inch to about two 
