40 



LINN^AN GENERA. 



lurking in the sand of the shore, where they may be found on the reflux 

 of the tiae : but also in rather deep water. 



Genus 10.— VENUS. 



Animal a Tethys; shell bivalve, the frontal margin flat- 

 tened, with incumbent lips ; hinge with three teeth, all of 

 them approximate, the lateral ones divergent from the tip. 



This genus is divided into two sections : pubentes * and impu- 

 bentes.** This latter section is subdivided into three families : sub- 

 cordate,t orbicular,tt and ovaLftt 



Venus Chiojie — The Chione Venus. Plate I. fig. 4. 

 (Cytherea Chione, Lamarck.) Shell strong, sub-cordated, 

 somewhat concentrically wrinlvled, margin entire, covered 

 with a smooth, glossy, chestnut-coloured epidermis ; some- 

 times a little radiated; beneath which the shell is of a beau- 

 tiful pale purple; apex turned sideways, with a cordiform 

 depression; umbo placed nearest one end. Inhabits the sea 

 at Falmouth in Cornwall. 



a a Summit, h h lunule, i anterior slope, fc posterior slope, o disk, p 

 margin or Umb. 



Venus compressa. — The Compressed Venus. Plate I. 

 fig. 9. (Crassina compressa, Leach.) Shell strong, thick, 

 suborbicular, compressed, and slightly sulcated or irregularly 

 wrinkled ; colour white, but is usually covered by a thick 

 yellowish-brown epidermis; umbo prominent, turning to one 

 side, beneath which is a small cordiform depression ; hinge 

 with two teeth in one valve, and a transverse one. Inhabits 

 the British seas, 

 c Sides, d base, e e cicati'ix, g g teeth of the hinge, to the imibo. 



Venus decussata. — The Decussated Venus. Plate I. 

 fig. 11. Shell ovate, with decussate striae, angular before; 

 apex turned to one side ; umbo placed nearest one end ; 

 hinge furnished with three teeth in one valve ; posterior 

 slope very minute and retuse ; anterior slope long and narrow, 

 with generally an inner blue margin. The outside is com- 

 monly of a plain rusty brown, and marked with purple zigzag 

 lines. Two inches long and three broad. Inhabits the 

 British seas. 



