BIVALVIA. 153 



17. Cardita corpusculum, S. Wood. Tab. XXI, fig. I, a, 6. 



JDiameter, \ a line. 



Locality. Barton [Edwards). 



A few specimens in Mr. Edwards's cabinet, of a very minute size, appear to belong to 

 this genus, and I have given to them the above name provisionally. They are of 

 a somewhat aberrant character, the cardinal denticle of the right valve being short 

 and triangular, like that oiAstarte, instead of being elongate. They have also a very distinct 

 and distant lateral tooth on the pedal side, prominent in the left valve, and interlocking 

 in a corresponding depression in the right. From this peculiarity of hinge I have imagined 

 this to be a distinct species, and not the young state of a larger kind ; it resembles in size a 

 small species of the Paris basin, figured and described by Prof. Deshayes under the name 

 of C. atomus, but it has more numerous and more distinct ribs, and our shell is more 

 orbicular. Pour specimens are in Mr. Edwards's cabinet, and two of these possess 

 a circular opening or zoophagous perforation. This is, I believe, GoodalJia granulosa, 

 Tennant, ' Strat. List Brit. Poss.,' p. 30, 1847. 



ASTARTE. J. Sowerby, 1816. 



Generic Character. Shell sub-triangular, sub-orbicular, or oblong, generally com- 

 pressed ; thick, strong, smooth or concentrically ridged, equivalved, closed ; hinge with 

 two diverging cardinal teeth in the left valve, with a triangular space between them for 

 the reception of a prominent tooth of the same form in the right, with generally a lateral 

 tooth or raised margin, and a corresponding depression for its reception in the opposite 

 valve ; adductor muscles deeply impressed, with a small pedal one within or above the 

 oral adductor; palleal line without a sinus; connexus ligamental. 



Animal with the edges of the mantle disunited; siphonal openings simple, not 

 extending beyond the shell ; foot rather small ; tongue-shaped. 



This genus comprises an interesting group of animals, and is largely developed in 

 the Upper Tertiaries in Europe, as also in America. It is found in this country in 

 Secondary Formations, where species are by no means scarce ; and it has been said to 

 indicate by its presence in any fossilliferous deposit the conditions of very diminished tem- 

 perature ; but it occurs in association with Tetrabranchiate Cephalopoda, the supposed 

 inhabitants of warm or tropical regions, and at such an horizon of the London Clay 

 (Highgate and Sheppey) as proves its very close synchronism with, and contiguity to, the 

 gigantic Ojjhidia, Chelonia, Crocodilia, and rich Plora of Sheppey. 



21 



