176 



ZOOLOGY 



/ 4 . Shells less than 20 mm. long ; 

 aperture with a notch near 

 posterior end, formed by 

 outer lip not squarely meet- 

 ing body wall . . . Pleurotomidce 

 /s. Shells less than 15 mm. long ; 

 aperture entire at posterior 

 end ; narrow, and a little 

 less than \ the length of 

 the shell ; canal rather 

 short .... ColumbellidcR 

 e. Canal short or absent ; aperture 



notched, 

 /i. Shells large, 40 mm. or more 



long ; whorls rounded . Buccinidw 



/ 2 . Shells 20-40 mm. long; 



whorls rounded . . Muricidce 



/s. Whorls flattened, surface 

 usually beaded ; aperture 

 over i length of shell , Nassidw 



Non-operculated, or operculum very mi- 

 nute ; aperture with neither a canal 

 nor a notch at anterior end. 

 d\. Aperture over f area and | length of 

 shell ; spire distinct, pointed ; shell 

 ear-shaped . ,. . . . Naticitlf.e 



do. Aperture \ the area or more, and the 



full length of the shell. 

 e\. Shell with 1 whorl, less than 2 



mm. long . . ... Philinidce 



2- Shell with several whorls, under 



4mm. long; spire flat , : . Scaphandridas 

 63. Several whorls, a pit in place of 



spire, over 6 mm. long . . Bull idee 



d s . Aperture less than i the area of the 



shell. 



e\. Aperture f to whole length of 

 shell ; spire distinct, usually 

 flattened ; under lip with single 

 fold or smooth Tornatinidw 



