ISOCARDIA. 69 



A. triangularis is very small^ and triaugular. 



A. compressa is flattish, finely grooved, more or less rounded 



or triangular. 

 A. elliptica is longer than A. DanmoniensiSj and is generally 



smooth towards the edge. 

 A. crehricostata is more nearly triangular than A. Danmo- 

 niejisis, with the grooves much more numerous and 

 regular ; of very rare occurrence. 

 A. arctica : large, rounded, and smooth. 

 lY. IsocARDiA cor. — Using the term in a conventional 

 rather than in a natural sense, the shell of this fine 

 Lish mollusc is not inappropriately described as 

 " heart-shaped,^' for it may be held in such a position 

 as to present a figure like nothing else in nature, but 

 remarkably like the article so commonly seen in shop 

 windows during February, painted red, and having 

 some sort of connection with an undressed urchin in its 

 vicinity. It is very full and rounded, and has large 

 spirally-curved umboes or beaks. 

 Following the example of others, whose powers of origi- 

 nality are unquestionable, I cannot help transcribing from 

 the ' Zoological Journal the very interesting account given 

 of this animal by the Rev. James Bulwer. 



