GASTEOPODA 



539 



lengthened snout; the animal adheres by means of the broad foot to 

 stories and shells, arid does not move about: 7 genera and 160 species. 

 Key to the genera of Capulidae here described: 



! Shell conical ; partition cup-shaped 1. CBUCIBULUM 



2 Shell with a slight spiral; partition more or less horizontal. . . .2. CBEPIDULA 



1. CRUCIBULTTM Schumacher. Shell, conical and not 

 spiral, with the apex directed posteriorly; shelf more or 

 less cup-shaped, attached to the inner wall near the apex, 

 on one side: cosmopolitan. 



C, striatum (Say) (Fig. 835). Cup-and-saucer limpet. 

 Shell solid, with numerous elevated radiating lines; aper- 

 ture circular; white or yellowish in color; 12 mm. in 

 height and /20 mm. in diameter : Florida to Bay of Fundy ; 

 in 2 to 189 fathoms; common in shallow water towards 

 the north. 



2. CREPIDTTLA* Lamarck. Shell oval, boat-shaped or 

 inconspicuous spire at the hinder end; shelf an internal 

 in the hinder half of the shell: 50 species, in all the 

 attached to shells, seaweed, etc. 



Key to the species of Crepidula here 



a T Shell convex. 



&! Shell up to 45 mm. long ; shelf white. . . . 



& 2 Shell 12 mm. long or less ; shelf brown. . . 

 a 2 Shell flat 



Fig. 835 



Crucibulum 



striatum 



(Verrill). 



flat, with the 

 regular plate 

 warmer seas; 



described : 



.C. FORNICATA 

 . . C. CONVEXA 

 . ...C PLANA 



Fig. 836CrepiO- 



ulum fornicata 



(Verrill). 



C. fornicata (L.) (Fig. 836). Shell convex, with 

 one side more curved than the other; color whitish or 

 brownish; shelf concave, white; length 45 mm.; width 

 33 mm. ; height 15 mm. : Nova Scotia to South America, 

 in shallow water, very abundant ; Europe. 



C. convexa Say. Shell very convex, the short side being nearly 

 vertical; color whitish or brownish; shelf deep-seated, convex, brown 

 in color, with a white edge ; length 12 mm. ; width 8 mm. ; height 4 mm. : 

 Nova Scotia to Florida, in shallow water; not so abundant as the above; 

 Pacific coast. 



C. plana Say. Shell flat or concave, with a minute apex; white and 

 polished inside ; length 40 mm. ; width 25 mm. : Maine to Texas ; common 

 in shells from low-water mark to 487 fathoms. 



FAMILY 3. LITTOEINIDAE. 



Shell spiral and conical; lip not notched; aperture round, interior 

 not pearly; operculum horny and spiral; head projecting, tentacles 



* See "The Embryology of Crepidula," by E. G. Conklin, Jour. Morph., Vol. 13, 

 1897. 



