MOLLUSCA OR UNIVALVES. 149 



them on the back of the animal near the neck, 

 projecting either within the cavity or above it. 

 The shells, in many instances, resemble the 

 Patella in form, though differing from it in 

 other particulars. They are always external, 

 and cover the animal. — 7 genera. 



21. Parmophorus. — Shell oblong, de- 

 pressed slightly, convex on the 

 outside; apex small, and some- 

 what inclining to one end. Ani- 

 mal, head rather indistinct, with 

 two tentacula, having eyes at the 

 base; foot very large. — There 

 are 3 species recent, and 2 fossil. 

 This genus is found in New Hol- 

 land and New Zealand. 



The interior exhibits very strong muscular 

 impressions, which are in some species marked 

 with a blood red colour. It is often called the 

 Duck's Bill Limpet. 



22. Emarginula. — Shell rather oblong, 

 with the apex curved, and 

 having a narrow slit or hollow 

 in the margin, generally rayed 

 on the outside. Animal, head 



L 3 



