JUKES-BEOWNE : CKETACEOUS AND EOCENE VENEEID-i:. 151 



M. Maurice Cossmann had recognized the existence of species of 

 Bosiniopsis in the Lower Eocene of France as far back as 1885/ but 

 he only gives a translation of Conrad's description of the type, and 

 then remarks: "The form of the sinus, the crenulation of the 

 nymph, and the (elongate) lateral tooth appear to me to justify the 

 creation of a genus and consequently the adoption of Conrad's." No 

 mention is made of a posterior lateral tooth. 



Dr. W. H. Dall seems to have been the first to recognize the 

 existence of posterior lateral teeth in Bosiniopsis.''' He gave a complete 

 fresh generic description, and mentions "the distinct posterior right 

 lateral which fits into an excavated socket in the left valve" ; then 

 adding: "This is the only genus of the family with a distinctly 

 developed posterior lateral tooth, and if it were not for the number of 

 cardinals and the presence of a pallial sinus it might be referred to 

 CyprinaJ'^ Dr. Dall, however, does not seem to have been aware of 

 Messrs. Clark & Martin's observations (as above quoted), for he 

 takes B. Meehi as the type, and his generic description includes the 

 word ' heavy ' as applied to the shell, and the words ' strong ' and 

 ' stout ' applied to the lateral teeth. It seems desirable, therefore, to 

 give an amended description of this genus, and I have drawn up the 

 following, after examination of English and French species, and 

 inspection of the excellent figures of the type form in the "Eocene 

 Deposits of Mai-yland." 



DosiNiopsis, Conrad, 1864. 



Types — Cytherea lenticularis, Eogers, and var. Meehi, Conrad. 

 Shell suborbicular or rounded- oval ; concentrically striated. Lunule 

 slightly impressed, but often indistinctly circumscribed ; escutcheon 

 not defined. Hinge generally strong, cardinal teeth three in each 

 valve, all separate and entire except the right posterior, which is 

 bifid ; a posterior lateral in each valve, that of the right, being the 

 stronger ; an anterior lateral in the left valve, elongate, parallel to 

 shell border, more or less rugose, and fitting into a corrugated pit in 

 the right valve. Nymphs of both valves finely granulated. Margins 

 of valves smooth. Pallial sinus ascending, not very deep, rounded or 

 angular. 



To Bosiniopsis I refer the Cretaceous shells hitherto known as 

 Cytherea caperata, Sow., and C. suhrotunda, Sow., both from the 

 Selbornian Sands of Blackdown. There are three species in the 

 Lower Eocene of the Paris Basin, and I think that all of them also 

 occur in our Thanet Sands and London Clay ; these are B. orhicularis, 

 Edw., B. fallax (Desh.), and B. lellovacina (Desh.). A fourth species 

 has been named iDy Edwards B. pseudorlicularis, but has not yet been 

 figured. 



2. DosiNiA, Scopoli, and Sinodia, n.subgen. PI. VI, Fig. 2. 



During my examination of the Cretaceous and Eocene Veneridse 

 I have been struck with the Dosinioid aspect of many of the shells, 



1 Ann. Soc. Malac. Belg., vol. xxi (1886), p. 125. 



• " Synopsis of the Family Veneridaj " : I?roc. U.S. Nat. Mus., vol. xxvi (1002), 

 p. 342. 



