140 CONCHYLIA— D/THFiJ^. 36. 



turned towards the hinder side, giving the shell a somewhat heart- 

 shaped appearance, with generally a heart-shaped impression under 

 the curvature of the beaks ; and the ligament is almost uniformly 

 placed in the excavated slope of the anterior or opposite side. 



And that the specific characters of this still multitudinous family 

 may be more clearly contrasted and understood, attention to the fol- 

 lowing definitions will afford much facility and prevent misconcep- 

 tion : cancellate, when longitudinal lines or striae are placed in the 

 interstices of the transverse ones, but do not pass over or cut through 

 them : reticulate, when longitudinal lines pass over transverse ones, 

 but do not cut through them : decussate, when longitudinal lines cut 

 through the transverse ones. 



The heart shaped depression under the curvature of the beaks is 

 denominated the areola : and the excavated slope on the opposite or 

 anterior side, in which the cartilage is deposited, is called the area; 

 the two sides of which are the lips. 



* Margine interno crenulato. 1-12. 



With the inner margin notched. 



f orhiculo-cordatw. 



orbicular heart-shaped. 



verrucosa. Venus testd globoso-cordatd, laminis transversis undulatis, laterihus 

 verrucosis, areola cordatd. 

 Shell globular heart-shaped, with transverse jagged plates, warty at 



the sides, and the areola heart-shaped. 

 Venus verrucosa. Linn. Syst. Nat. p. 1130. 

 Gmelin. Syst. p. 3269. 



1. 



