TRANSACTIONS OF WAGNER 

 756 



TERTIARY FAUNA OK FLORIDA 



Nepionic left valve with obsolete radii and often feeble concentric undulations: 

 P. precursor Dall. 



Nepionic left valve with distinct flattened ribs with shallow channelled inter- 

 spaces crossed by concentric, evenly spaced, not crowded, elevated lines : 

 P. Lyoni Gabb. 



Left valve of the adult with obsolete rounded ribs extending, in the adult, 

 well over the middle of the disk : P. ocalanus Dall. 



P. precursor is nearly as large as P. Mortoni, but slightly rougher and 

 more convex when adult, the young are nearly orbicular ; a distinct trace of 

 Camptonectes striation, near the beak and submargins, may be discerned with 

 a magnifier in a good light. Alt. no, lat. 123, diam. 20 mm. The right 

 valve is much flatter than the other. As the material is much broken up, it 

 seemed hardly worth while to figure it. 



Pecten (Amusium) ocalanus n. s. 

 PLATE 29, FIGURE 2. 



Oligocene of the Vicksburgian at Natural Bridge, Alachua County; at 

 various localities in Levy County; at Arredonda and Archer; Newnansvillc 

 and Johnson's lime sink; and in the Nummulitic horizon at Ocala and Martin 

 Station, Marion County, Florida; also in the Vicksburgian of Alabama; 

 Dall, Burns, and Willcox. 



Shell of moderate size, nearly equivalve, quite inequilateral, moderately 

 convex; right valve with the disk nearly smooth, posterior margin produced; 

 ears subequal, nearly smooth, their outer angles a little raised, so that the 

 cardinal margins form a very obtuse angle at the beak ; byssal sinus repre- 

 sented by a marked flexure but not a distinct notch ; left valve similar, 

 slightly more convex, with about eighteen obsolete rounded ribs, separated 

 by narrow, shallow grooves, sharpest near the beak, radiating nearly to the 

 basal margin but becoming less visible there and at the submargins; ears ver- 

 tically striated, subequal ; interior of the disk with about twenty-one pairs of 

 well-marked lirae similar in each valve ; hinge with developed cross-striated 

 cardinal crura, auricular crura present; margins of the valves smooth, not 

 crenulated. Alt. of figured shell 35, lat. 35 ; alt. of largest specimen 43 mm. 



The fossils vary from nearly smooth to obviously ribbed ; the byssal 

 sinus is more distinct than in the other species and sometimes verges on a 

 notch, and there is a perceptible byssal fascicle. 



