298 THE SHELL-FISH OF THE COAST. 
head and tentacles. It is a powerful excavating 
implement, and by it the animal is enabled to bur- 
row in the sand like a mole. The Natica is blind, 
being destitute of eyes. 
Of the three species of our coast the commoner 
forms are the two large species known as Natica 
heros (Pl. 1, Fig. 1) and Natica duplicata (Fig. 4): 
NIDUS OF NATICA HEROS, 
the first may be recognized by its larger size and 
more globular outline, and in having a deep hole 
(umbilicus) immediately alongside the aperture. 
In Natica duplicata the shell is more depressed and 
Nipvus oF NATICA DUPLICATA. 
somewhat oblique, while the umbilical aperture 
is closed by a thick ‘callous’ expansion. The 
third species is Natica pusilla. In your rambles 
