410 BULLIDiE. 



(usually three) calcareous or horny plates. Both sexes com- 

 mon to each individual. 



Shell convolute, external or internal : epidermis thin : 

 spire mostly short, frequently truncated or concealed : mouth 

 extending the whole length of the shell, or the greater part 

 of it ; it is entire (i. e. not channelled) at the base : outer lip 

 having a prominent and sharp edge : operculum very seldom 

 present. 



As to the characters founded on the tongue, Loven 

 says, " Typns armaturse lingualis vagus : " this is not a 

 strong recommendation of the odontological system. 

 The structure and anatomy of Bulla, Scaphander, and 

 Philine have been admirably investigated by Cnvier; 

 he first showed the affinity of the last-named genus to 

 Aplysia. Some of the Bullidce are zoophagous, others 

 feed indifferently on fresh or decayed animal matter. 

 The former swallow their prey (which chiefly consists 

 of other mollusca) entire ; and the calcareous plates of 

 the gizzard, moved by muscles of great strength, serve 

 to crush the most solid shells. This family does not 

 appear to be ancient. According to Mr. Searles Wood 

 a species of Bulla has been found in the Cornbrash, and 

 another in the Wealden formation. Many are tertiary ; 

 and the existing members of this group have a very 

 wide geographical and bathymetrical range. Most of 

 them are truly marine, while a few prefer brackish 

 water ; all live in sand and ooze or in 



. . . . " the slimy bottom of the deep." 



Bonanni and Gualtieri called the present family " nux 

 marina," D'Argenville u gonclole," and Pennant " dip- 

 per." It is the Bullaina of Macgillrvray. 



Genus I. CYLICH'NA*, Loven. PL VIII. f. 1. 



Body containable within the shell : mantle thickened at the 



* A medicine-box. 



