()8 



isocardioides,) a minute fossil in many respects closely re- 

 lated to it, but said by Lea to be destitute of teeth : as he 

 says nothing about the ligament, but mentions the close ap- 

 proach of its general characters to those of Isocardia, it is 

 probable that the ligament winds up under the beaks as in 

 that genus, and so Philippi describes it in his H. acuticos- 

 tatus. The general form of Lea's type of Hippagus is very 

 different, but the resemblance of the hinge is great, and 

 he says the edge of the shell is toothed ; upon the whole 

 therefore we adopt his genus for this shell, but with doubt, 

 and have made some additions to his Gen. Char, with a 

 view to its including both shells. The name Verticordia 

 was hastily adopted on early impressions of the plate from 

 Mr. Wood's manuscript, but is objectionable, having been 

 long ago applied to a plant. 



HIPPAGUS ? cardiiformis. 



TAB. DCXXXIX. 



Spec. Char. Convex, orbicular, costated ; costae 

 15or 16 prominent, obtuse, rugosely squamosa^ 

 projecting beyond the edge, furrows finely 

 granulated ; umbones incurved. 



Syn. Cryptodon Verticordia, 8. V. Wood, Caial. 

 Ann. and Mag. Nat. Hist. v. vi. 247. 



An orbicular shell, rendered beautiful by the curvature of 

 its ribs and almost pectinated margin ; internally the ribs 

 are indicated by slight furrows. It is produced by the co- 

 ralline Crag of Sutton ; about twenty individuals, single 

 valves, have been found. 



Hippagus acuticostatus (Phil. Enum. v. ii. ^l. tab. 14-. 

 f. 19.) is distinguished by sharp lamellar ribs, of which 

 there are only 13, not 15 or 16 which our shell has, and 

 by the corresponding furrows within being confined almost 

 to the margin, neither do they project so far beyond the 

 edge of the shell ; in size and other respects the two shells 

 hardly differ. 



