LAMELLIBRANCHIATA. 117 



MoDiOLA PEDERNALis, Roemer ? 



(Plate VI., fig. 2, a, b.) 



Modiola pedernalis, Roem., Kreide Texas, pi. vii., fig. 11. 



The ribs are very delicate in our Upware shells, and the 

 cardino-lateral border is straighter and less curved than in 

 Eoemer's figure, but having compared it with specimens from the 

 original locality in the Gottingen Museum I believe them to be- 

 long to the same species. 

 Locality. Upware. 



N. Europe. EUigserbrink, Hils Thon. 



Friedrichsberg, in Texas, America. 



Modiola obesa, sp. nov. 

 (Plate VI., fig. 3, a, h.) 



Description. A very obese species, elongated, oval, gibbous, 

 and arcuated. Cardinal and cardino-lateral borders forming 

 together one simple curve ; pallial border markedly sinuated ; 

 anal border narrow and rounded. The umbones are nearly ter- 

 minal, slender, depressed and incurved ; an arched shoulder runs 

 from them to the front limit of the anal border. Buccal area 

 swollen, marked off by a shallow furrow running alongside the mesial 

 shoulder, — its pallial termination corresponding with the sinus, 

 which is situated towards the posterior end, nearly two-thirds of 

 the whole length from the umbo. 



The surface is marked only by delicate laminae of growth, and 

 coarser growth-stages. 



Measurements. Length, 21 mm. ; breadth, 10 mm. ; thickness 

 (through both valves), 13 mm. 



Affinities and differences. A shell of the Modiola cequalis type, 

 also approaching near to M. Montmolini of MM. Pictet and Cam- 

 piche, Terr. Cret, St Croix (pi. cxxxiii., f. 2) ; from both of these 

 it is distinguished by the regularly-arched cardinal side, instead of 

 having a distinct cardinal angle. 



