TRANSACTIONS OF WAGNER 

 600 



TERTIARY FAUNA OF FLORIDA 



indicate the presence of any resilium at this point, while in Cyrilla the broad- 

 ening of the plate has disappeared. The teeth of the anterior group in P. 

 ova/is are bent Hke a half-open book standing on its base. There are three 

 of them and they are very elevated. In position they resemble those of P. 

 Woodii ; they are thin and compressed. The posterior teeth in horizontal 

 section are rounded, they are stouter, not so close together, not bent, and 

 rather conical. The widening of the hinge-plate in this species is not great, 

 and the posterior cardinal teeth rise almost directly from its inner margin. 



Pleurodon Woodii n. s. 

 Plate 24, Figure 10. 



Pliocene marls of the Caloosahatchie, Florida; Dall. 



Shell small, smooth, oval, slightly truncate in front, very inequilateral ; 

 sculpture only of extremely fine incremental lines, visible only under magni- 

 fication and stronger towards the margin ; beaks small, prominent, anterior ; 

 margins internally smooth ; hinge-plate wide, extended po.steriorIy more than 

 half the length of the shell, its lower edge distally turned up and thickened 

 to form a lateral tooth, to which in the right valve is added a small dorsal 

 thickening or lamina; anterior teeth small, three in each valve, the hinge-plate 

 slightly angular below the commissure between the anterior and posterior 

 cardinals ; posterior cardinals three in the right, four in the left valve, larger 

 than the anterior teeth and separated from them by a slight gap, the hinge- 

 plate grooved between them and its ventral margin. Lon. of shell 2.75, alt. 

 1.75, diam. i mm. 



This species differs from P. ovalis in the groove and angle of the hinge- 

 plate, but in other respects the teeth are much alike, and the two species are 

 closely related and of nearly the same size, P. Woodii being a trifle larger. 



P. viiliaris Deshayes, when fully adult, is larger than the P. ovalis and has 

 one more posterior tooth ; the anterior teeth are flatter, more compressed, and 

 more crowded together. The young resemble the P. ovalis more closely. 

 The adults have the ligamentary fossette completely covered. The specimens 

 were received from Dr. P. Fischer by Jeffreys. 



P. Reussii Deshayes, from the Tertiary of Bohemia, which was referred to 

 P. miliaris by Reuss, I have not been able to examine. 



P. calabrm Seguenza, from the Tortonian Miocene, I have not seen, nor 

 do I know if it has been described and figured. The name occurs in the list 

 of the fossils of the various Tertiary beds of Reggio in Calabria. 



