TRANSACTIONS OF WAGNER 

 I 122 



TERTIARY FAUNA OF FLORIDA 



In typical Solecardia there is a narrow, external ligament, which leaves 

 very little trace of its insertion on the shell, and a strong internal resilium with 

 a good deal of calcareous matter ventrally distributed in its substance but not 

 consolidated into an ossiculum. The external ligament is usually ignored in 

 descriptions of Scintilla, but it exists more or less developed in all the fresh 

 specimens of this genus which I have been able to examine. It is stronger in 

 the type mentioned than in some of the others, but in all there seem to be some 

 traces of it. 



It does jiot seem advisable, in the absence of anatomical data and authorita- 

 tive material, to attempt at present any subdivision of the recent Scintillas, 

 although it is quite possible that the group as it remains is not thoroughly 

 homogeneous. The fossil forms of the Paris basin, however, do not seem to 

 agree in character with the typical Scintilla and, with a number of American 

 Tertiary species, require to be eliminated from the subgenus. 



The essential characters of the several groups are as follows : 



Genus Solecardia Conrad. 



Shell partially covered by the mantle with an amphidetic obsolete externa! 

 ligament and an oblique internal resilium, without a lithodesma; right valve 

 with two divaricating, well-defined lamellae on 'each side of the resilium; 

 left valve with a single lamella on each side fitting between those of the 

 opposite valve ; hinge-plate excavated ; adductor scars rounded, small, situ- 

 ated within and distinct from the pallial line; valves subequilateral, with low 

 beaks, the surface more or less punctate. Type 5". eburnea Conrad, 1849. 



PSubgenus Scintilla Deshayes (em.). 



Shell almost wholly covered by the mantle, with an amphidetic obsolete 

 external ligament and an oblique internal resilium, without a lithodesma ; right 

 valve with one or two short anterior and one or rarely two feeble posterior 

 lamellae on the hinge-plate; left valve with two (rarely one) anterior lamellae 

 and one, or rarely two, behind the resilium ; hinge-plate flat or excavated ; 

 adductor scars ovate, continuous with the pallial line; valves subequilateral 

 with low beaks, the surface polished, smooth, radiately striate, or punctate. 

 Type S. philippinensis Deshayes, 1855. Scintillnla Jousseaume, 1888, belongs 

 hereabouts. The teeth in Solecardia are clean cut and strong; in Scintilla, 

 being practically functionless, they appear obsolete and rather shapeless; as 

 a rule, only one is at all distinct. In Solecardia the valves appear to close all 

 round, in Scintilla there is more or less of a gap between them, sometimes even 



