61 



but much deeper. The flat side and the want of longi- 

 tudinal furrows shew that it is not I. Lamarckii of 

 Parkinson, in the Geological Trans, v. V. p. 55. with 

 which, according to his figure, Mr. Mantell has however 

 confounded it. It agrees better with the description of 

 Mantell's I. Brongiarti, but not well with his figure of 

 that species. 



In Chalk, not uncommon. 



The hinges here figured, serve well to illustrate the 

 Generic characters. 



INOCERAMUS cordiformis. 



TAB. CCCCXL. 



Spec. Char. Equalvalved, heartshaped, trans- 

 versely and interruptedly waved ; beaks 

 large, incurved ; anterior side angular. 



A HE posterior side of this shell is not defined ; but 

 rises gradually from a hollow beneath the incurved 

 beaks ; the transverse waves are very high, and irregu- 

 larly interrupted ; the width and depth are equal and but 

 little exceeded by the length. The general form reminds 

 us of Isocardia Cor, only that the hinge line being pro- 

 duced, gives an angular form to the anterior side. 



The figure is taken from a remarkably fine specimen, 

 filled with Flint, that was found at Gravesend. 



