UNIVALVES. 



PLATE XXIII. 



Genus. CYPR^A. 



Character. Shell generally oval and orbiculated ; cheek of the mouth folded 



inwards ; the mouth narrow, and wholly covered on each side with teeth ; the apex 



generally obscure. 



Species. 



No. 1. Cypr^a alga. Shell of a pale flesh-colour, adorned with a pattern resem- 

 bling Arabic letters ; on the back of the shell is the form of an alga, or sea 

 weed ; mouth flesh-coloured, and spotted irregularly with red spots. This 

 shell, so singular in respect to its marks, is a native of the Cape of Good 

 Hope, and other parts of South Africa. 



No. 2. Cypr^ea valentia. Shell with a high and prominent summit, having the 

 ends marked with four ridges of a dark brown colour, and reverted at the 

 corners, forming a most beautiful and singular ornament ; the middle yellow, 

 shaded mapwise with red ; sides pink, spotted with dark red ; mouth of a 

 pale brown colour ; at the centre of the shell a dark red shadow, in the 

 form of a honeycomb. This elegant shell, which is very rare, and hitherto 

 a non-descript, was obtained from Amboyna by Lord Valentia. 



No. 3. Cypr^ea dama. Shell dark brown, with hair marks at the sides, wholly 

 interspersed with round white spots of different sizes ; the mouth pale brown; 

 the ends of the shell white. A native of Surinam. 



No. 4. CYPRiEA stolida. Shell nearly white, inclining to green, beautifully va- 

 riegated with quadrangular spots of brown on the back and sides ; inter- 

 spersed with small spots of red ; mouth pale brown. A native of Madagascar, 

 and drawn from a shell in the Museum of Lord Valentia. 



No. 5. Cyprjea misella. Shell ornamented with three bands of dark pink colour, 

 on a light pink ground, the former shaped into angular lines, two dark 

 spots at each end. 



No. 6. CYPRiEA gemmosa. Shell of a transparent white, varying to a gray, and 

 in parts to red, longitudinally divided from end to end with a deep furrow. 

 A native of the Eastern Seas. 



No. 7. Cypr^ia cicercula. Shell white, without any polish ; the ends much acu- 

 minated, and the form curious and singular. Native place unknown. 



REMARKS. 



The genus Cypraeahas been supposed by former writers on Conchology, to have the power 

 of enlarging the shell by continuing the mouth farther round, and by means of additional 

 layers. The increase of their bulk, however, is found to be performed in a very different 

 way, being effected by increasing the layers on each side alternately, that is, by adding to 

 the body as well as to the lip, by external layers. The Strombus seems to increase its lip 

 only, by external layers. Nothing can be more surprising than the growth of marine shells, 

 and the manner in which the animal applies the viscous mixture, for the substance, and the 

 coating or enamel, forming a beautiful varnish, and incapable of solution in the watery ele- 

 ment in which it is contained. These shells being of a strong texture, are usually found 

 in good preservation. 



