FREE INSTITUTE OF SCIENCE 



I I 70 



TERTIARY FAUNA OF FLORIDA ' ^ 



ment and a resilium present, contrary to Recluz's impression, and the state- 

 ment that there is a palHal sinus is erroneous. It is true that a little behind 

 the middle of the shell there is a roughly quadrate polished patch or area ex- 

 tending upward, much as figured by Recluz (J. de Conchyl., ii., pi. 2, fig. 11), 

 but a careful examination of this area shows that it is not due to a sinus in the 

 pallial line (which passes regularly below it, as in Diplodonta, without any 

 flexuosity) , but to the attachment to the shell of a localized area of the mantle 

 above the pallial line. According to Mittre, there is a single (anal) opening, 

 not produced into a siphon, as in Ungulina, and therefore nothing which 

 would require the attachment of siphonal retractor muscles to the valve. 

 Felania, however, differs from Diplodonta in possessing a lunule, small but 

 sharply circumscribed, and until more is known will best be kept separate. 

 Both Diplodonta and Ungulina agree in having usually an amphidetic extension 

 of the ligament as well as an internal resilium, united in the former but divided 

 in the latter. The resilium is small and nearly external in Diplodonta, large 

 and internal in Felania and Ungulina, marginally in contact with the ligament 

 in Felania, but subvertical and separated in Ungulina. The teeth are essentially 

 the same in all three, but more rugose and irregular in Ungulina. Many of the 

 species commonly referred to Felania do not agree in character with the type 

 of that group, but form a section of Diplodonta. I have seen no species which 

 could be referred to Felania in the strict sense except the two named by Recluz. 

 It will be necessary to examine the anatomy of Felania before it can be defi- 

 nitely settled whether it will form a distinct genus or merely a subgenus of 

 Diplodonta. H. and A. Adams refer to the foot of D. lupinus as compressed, 

 but this is probably due to an erroneous observation of Clark on a young D. 

 rotunda, since D. lupinus is a fossil unknown in the recent state. Cycladicama 

 Val. appears to be a synonym of Diplodonta proper. 



Sphwrella Conrad is founded on a single species, S. subvexa Conr., from 

 the Miocene of Virginia, which has some distinctive characters, the most 

 important of which are, (i) the unusual position of the posterior adductor 

 scar, which is placed low down, its upper end hardly rising above the ventral 

 end of the anterior scar; and (2) the form of the right posterior cardinal 

 tooth, which is much more transverse and larger than in ordinary Diplodonta. 

 Conrad referred many globose species of Diplodonta to Sphcerella, but I have 

 seen but one other American species which presents the distinctive characters 

 of Spharella. Among recent forms there are a few, of which Diplodonta sene- 

 galensis Reeve is the most conspicuous, which have low-set posterior adductors, 

 but this species has the ordinary teeth of Diplodonta. It is evident, therefore. 



