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POPULAR CONCHOLOGY. 



to the spot they have once fixed upon, from the circum- 

 stance that the form of the margin of the shell agrees 

 exactly with the portion of rock on which they live, and 

 preserves the same form to adult age. The P. Ungarica, 

 the Hungarian cap or bonnet, of the British Seas, has the 

 inside bright, and often of a beautiful rose colour ; the 

 outside nearly white, and covered with a shaggy but very 

 soft epidermis. It is said that they sometimes form a 

 shelly disk from the foot. 



Those species which Defrance named Hipponyx are 

 thus described and figured : — 

 Shell, obliquely cup-shaped, 

 and sometimes, perhaps gene- 

 rally, supported on a solid 

 shelly plate; the shell and 

 plate exhibit two strong mus- 

 cular impressions, which are in the form of a horse-shoe. 

 Animal similar to Capulus. 



Sowerby, in his " Genera of Shells," contends that 

 these shells are bivalves ; but the opinion has not been 

 adopted, and the examination of the animal inhabitant 

 must at once determine the subject. 



Philippi adds the following as sub-genera : — Amathina 

 Gray ; Hipponyx Defrance; Sabia Gray. 



Brochia. Bronn. — Shell oblique, and globularly co- 

 nical, bonnet-shaped ; the apex is towards the back, and 

 rolled spirally, so that the spiral part is almost perpen- 

 dicular to the edge ; the aperture is almost circular, at 

 the right side there is a deep sinus ; a strong fold rises 

 between the sinus and the hinder edge, and is prolonged 

 as far as the apex ; the muscular impression is lengthened, 

 curved, and oblique. (No under calcareous plate.) — 2 

 species, fossil. 



