28 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 Naiica 

 heros (PI, 1, Fig. 1) and Naiica duplkaia (Fig. 4): 



Niuua OF Natica hekos. 



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 Naiica duplicata the shell is more depressed and 



Nidus op Natica duplicata. 



somewhat oblique, while the umbilical aperture 

 is closed by a thick ' callous' expansion. The 

 third species is Naiica pusilla. In your rambles 



