TRANSACTIONS OF WAGNER 

 660 



TERTIARY FAUNA OF FLORIDA 



The fossil Pinnas are very difficult to handle, as the fibrous layer is often 

 entirely lost, the fragile shell is almost invariably crushed and fragmentary, 

 while internal casts are defective in the external ornamentation. For this 

 reason the literature says very little in regard to the genus in our Tertiaries, 

 and only one species has been formally described. 



Genus PINNA (Jv.) Lamarck. 



Pinna quadrata n. s. 



Plate 29, Figure 7. 



Shell straight, thin, acute anteriorly with the valves mesially carinate, 

 the dorsal and ventral areas making about the same angle at the carina as 

 the valves do at the hinge-line ; byssal gape long, extending well towards the 

 beaks, narrow behind; sculpture of some five longitudinal ribs on the dorsal 

 areas and two or three below the carina, the surface near the ventral edges 

 almost smooth. Lon. of type 56, vert. diam. 26, carinal diam. 25, apical 

 diam. 6.5 mm. 



A single internal cast was collected by Mr. Willcox at Richard's quarry, 

 Ocala, Florida, in the Nummulitic or Ocala horizon of the Vicksburgian 

 Oligocene. Specimens nearly twice as large as the above-mentioned were 

 found by L. C. Johnson at Johnson's lime sink, Levy County, and Arredondo, 

 Alachua County, Florida, in the Vicksburg limestone. They are remarkable 

 for their rapid increase in diameter. 



Pinna caloosaensis n. s. 

 Plate 26, Figure 4. 



Shell long, slender, straight, narrow, thick, with the valves moderately 

 rounded ; carina not conspicuous in the fossils, but the sulcus very long, deep, 

 and sharp, represented on the interior by a large rounded rib; dorsal area 

 sculptured with about three feeble irregularly longitudinal ridges ; ventral 

 area with about the same number, but stronger and sharper. Lon. of type 

 120, max. dorso ventral height 40, min. do. 10, convexity of the valve at the 

 sulcus behind 12 mm. 



A single broken valve without the fibrous layer and the apical part of 

 another was obtained from the Pliocene marl of the Caloosahatchie. 



This species is not unlike P. riidis in form, but is proportionally much 

 thicker and the sulcus is much larger than in the recent shell, which has no 

 such strong, rounded internal rib. • 



