777 A; HLUG AND ITS ALLIES 



IfW 



shell is about 150 millimetres long, and pear-shaped. In 



one species the margins of the whorls are grooved (Fig. 



157) ; in the other they are carried out 



into thorns. The egg-cases are tough 



and membranaceous and resemble rows 



of coin strung on a string, the whole 



being slightly coiled. 



In Urosalpinx 1 the canal is short (Fig. 

 158). This typical representative of the 

 Muricidse is everywhere abundant on our 

 Eastern coast. It is much hated by 



/ 



oystermen, by whom it is known as the 



"oyster drill." It bores through the FIG. 158 - - Urosal- 



J pinx, the oyster 



shell of this and other bivalves bv means 



*/ 



of its radula and sucks out the contents 

 through the hole. 



Crepidula, 2 the boat shell or " decker," represents a 

 type in which the spire has become almost obsolete. It is 



drill. Nat. size. 

 Photo, by W. H. 

 C. P. 



FIG. 15U. Crepidula, the boat shell. Two-thirds nat. size. Photo, by 



W. H. C. P. 



still represented, however, in a rudimentary way at the left 

 of the aperture (Fig. 159). The modified shape is associated 

 with the habit the mollusk has of lying, aperture down- 



1 ovpd, tail ; adXiriy^ a trumpet. - A small sandal (crepidcC). 



