18 VENUS. 



each valve, the middle dnes a little cloveo : length hardly 

 three-quarters of an inch; breadth a little more. 



It differs from V. aurea^ in its colors, in the angular out- 

 line of the cartilage side, in not being regularly convex but 

 merely tumid in the middle, and in sloping to a sharp edge 

 especially on the angular side< 



In the blue clay of Clontarf, in Ireland, v. m. 



34. Venus aenea. Bronzed Venus. Fig. 20. 



Shell oval, convex, brittle, rather thick, covered with a 

 shining deep copper-colored skin under which it is chalky 

 white, rounded at one end, regularly tapering and much 

 produced at the other, where it is also rounded, but not 

 forming the least angle at the termination of the cartilage, 

 with numerous close-set regular transverse striae, and a 

 few deep furrows at the margin, marked. also with some 

 very minute longitudinal lines : beaks much pointed, near 

 to and turning towards the larger end, with an elongated 

 heart-shaped depression under them: teeth strong* two 

 of them cloven in one valve and one in the other : inside 

 white, with the margin rather obtuse and plain : length an 

 inch ; breadth one and a haU'. 



This beautiful species, so totally differing from all which 

 wehave examined, in its elegantly tapering shape and bright 

 coppery skin, we found abundantly buried in the blue clay, 

 at Clontarf near Dublin, v. m. 



35. VenUs siriuosa. Indented Venus* 

 Pennant, pi. 58. f. A. 



Shell roundish-oval, a little produced at the posterior end 

 and much broader on the cartilage side, yellowish white; 

 glossy, marked with numerous broad and flat concentric 

 ribs, which do not run into rough ridges or wrinkles at either 

 of the sides, with a deep depression in the middle forming 

 an indentation on the front margin^ and a corresponding 

 ridge on the opposite surface : this sinuosity or cavity com-< 

 mences a little way from the beaks, and becomes broader 

 and deeper towards the margin ; inside yellowish, with the 

 margin plain and very obtuse : beaks quite central, rather 

 prominent, a little inclined to one side, with a heart-shaped 



depress ion 



