TRANSACTIONS OF WAGNER 

 776 



TERTIARY FAUNA OF FLORIDA 



teen by fifteen centimetres, being somewhat wider than high. The chondro- 

 phore is almost sessile, so short is the peduncle ; the scar of the byssal 

 foramen is very distinct, about two millimetres in diameter and ten millimetres 

 below the base of the chondrophore. So small is the play of the valves that 

 the cardinal border, scnso stricto, has ceased to exist, and the convex valve has 

 that margin flattened and produced dorsally, taking on a patelliform character. 

 The elevated lateral margins of the ligamentary scar are clearly of dynamic 

 origin and not developed crura. 



A singular fact is that the convex valve retains several of the sessile 

 plugs of a large Anomia and adherent portions of their valves. 



This species has no cardinal area, the surface is radiately striate and of 

 that talcose aspect proper to Placenta and Ephippium ; the distal portion of 

 the chondrophore bears traces of a reflexed lamina like that we figure for our 

 Floridian form (pi. 24, fig. 6 A). This character again is obviously dynamic, 

 and is probably absent in young and perhaps some adult specimens. 



Carolia (Carolia) jamaicensis n. s. 

 PLATE 33, FIGURE 21. 



Eocene (?) of the Cambridge beds, Cambridge, Jamaica ; R. T. Hill. 



Shell of moderate size and irregular growth, extremely compressed, thin, 

 normally suborbicular ; upper valve slightly convex, with inconspicuous beak 

 and no clearly defined cardinal area; surface of both valves covered with 

 fine, vermicular, close-set radial striae and threads ; lower valve flat, the fora- 

 men indicated by a small tubercle which in the course of growth comes to 

 lie almost directly under the wide, little-elevated chondrophore; adductor 

 scar subcentral, rounded; shell silvery, subnacreous. Alt. of portion figured 

 (broken) 40, lat. 47, diam. 5 mm. 



These shells were found mixed in with the remains of Karrettia and 

 Rudistes of several species which appear to be standing in the limestone 

 in the position in which they grew, in what Professor Hill calls the Cambridge 

 formation and refers to the Upper Cretaceous. Considering the relations of 

 the genus, I cannot regard the Carolia as Cretaceous, and prefer to look at 

 it as either a subsequent deposition, or as possibly having grown upon 

 previously fossilized Cretaceous Rudistes upon which an Eocene sea had 

 encroached. This view is supported by the presence of other fossils of 

 unmistakably Eocene facies in the limestone in which the Carolia occurs. 



