TRANSACTIONS OF WAGNER 

 74 



TERTIARY FAUNA OF FLORIDA 



mens, the ribs are more rounded. On the whole, the species appears to be 

 sufficiently well discriminated. 



The only other described Eocene species from the Atlantic coast is P. 

 anisopleura Conrad (Kerr, Geol. N. Car., App., p. 18, 1875), the type of which 

 is a large, heavy shell which has lost its hinge, and was collected by Dr. Yarrow 

 " forty miles south of Beaufort, North Carolina," which would put its locality 

 near New River, Onslow County. It is of ovate shape, with large, squarish 

 ears, and very irregular, large, radial, strongly but sparsely scabrous ribs, 

 rounded above with two or three smaller riblets on each side more depressed 

 than the centre of the rib. Alt. 85, lat. 70 mm. The shell is much bored by 

 pholads and badly wormeaten and worn. It looks like a dilapidated valve of 

 Hinnites or Spondylus, and its horizon is entirely uncertain. 



Pecten (Chlamys) alumensis n. s. 

 PLATE 34, FIGURES 10, n. 



Oligocene of the Chipola horizon, in the lower bed at Alum Bluff, 

 Chattahoochee River, Florida ; Ball. 



Shell small, thin, with compressed, flattish umbones and fourteen or 

 fifteen feeble, obsolete ribs on the lower part of the disk separated by equal 

 shallow interspaces; the whole surface marked with fine concentric lines; 

 ears subequal, concentrically striate, not radiated, except the byssal ear, which 

 has five scabrous riblets and a well-marked notch ; interior fluted to corre- 

 spond with the external ribs; the cardinal crura developed. Alt. reaching 

 15-18 mm. in fully adult shells; figured specimen 8, lat. 7.5 mm. 



This small shell is sufficiently distinct in its characters to indicate its 

 specific rank, though it may be that it attains a larger size when adult than 

 any of the specimens obtained. One or two of the specimens have the ribs 

 more rounded and prominent than the majority. 



Pecten (Chlamys) tricenarius Conrad. 



Pecten tricenarius Conr., Proc. Acad. Nat. Sci. Phila., i., p. 306, 1843 ; Fos. Medial 

 Tert., p. 74, pi. 42, fig. 2. 



(Miocene?) Pamunkey River, Virginia; Tuomey. 



Of this species only the type is known, and the horizon is uncertain. It 

 has somewhat of the outline of P. pcrplamts, but has a smaller shell and 

 larger ears. The disk shows thirty-five rounded, nearly smooth, not dichoto- 

 mous ribs, somewhat irregular in size, will) equal interspaces, smooth and 



