TRANSACTIONS OF WAGNER 

 1 132 



TERTIARY FAUNA OF FLORIDA 



Basterotia C. Mayer, in Homes, Fos. Wiener beckens, ii;,"p. 40. Type B. corbuloides, 

 op. cit., pi. iii., fig. ii, 1870; Ball, Blake Moll., p. 316, 1886; not of Bayle (MS. Me 

 Jousseaume), 1884. 



This genus has been associated with the Corbulas, which are not closely 

 related to it, with Poromya, and with the Cypricardians. The general features 

 of the soft parts have been described by Fischer, but his account is not suffi- 

 ciently detailed to enable us to locate it definitively. At present all that can 

 be said is that it may belong near Haloconcha or in the vicinity of Sportella. 



As far as can be judged at present the genus is divisible into the following 

 sections, which are not separated from each other by any very distinct char- 

 acters : 



Section Basterotia Mayer, 1870. 



Shell inflated, quadrate, carinated behind, more or less gaping behind and 

 ventrally, with a granular surface sculpture, glassy texture, and simple pallial 

 line; hinge with a single prominent denticle under the incurved beaks sepa- 

 rated by a gap from a short dentiform nymph bearing an external ligament. 

 Type B. corbuloides Homes. 



Section Fulcrella Cossmann, Cat. 111. bas. Paris, i., p. 136, 1886. Type 

 Poromya paradoxa Desh. 



Shell like Basterotia but without posterior carina, the surface usually con- 

 centrically striate and not granular; rounded quadrate, the tooth less promi- 

 nent, the nymph longer, and without any conspicuous notch or gap between 

 it and the tooth, and the valves more or less close fitting. 



Section Anisodonta Deshayes, 1858. Type A. complanata Desh., op. 

 cit., pi. xxii., figs. 1-4 (bad). 



Shell elongated, more or less carinate and pointed "behind, beaks not con- 

 spicuous, valves gaping little if at all, surface granulose, teeth moderately 

 developed ; nymph rather elongate, not prominent. 



The original type specimen was diseased and consequently the figure is very 

 misleading. The identification has been cleared up by M. Cossmann. The 

 distinctions between the three sections are very slight. 



The relations of the genera Passya Desh., and Fabagella Cossmann (i., p. 

 41, 1886, type F. faba (Desh.), pi. ii., figs. 40-41) to Basterotia will bear 

 investigation. 



