FREE INSTITUTE OF SCIENCE 



715 



TERTIARY FAUNA OF FLORIDA 



Mr. Reid remarks that Sowerby's description was apparently mainly 

 drawn from I?, and that the two forms are so distinct that it is difficult to believe 

 that Sowerby can have referred them to the same species. In the absence of 

 a figure we may adopt B as representing the name, which would agree with 

 usage as seen in the Guppy and other collections. The other specimens (A) 

 seem from the remarks cited to be nearest to some varieties of oxygoiiuui or 

 iveeqwalis. 



Pecten (^Equipecten) scissuratus n. s. 

 PLATE 34, FIGURR 4. 



Oligocene of Ponton, St. Domingo, and ten and a half kilometres west 

 of Colon, Isthmus of Darien ; Hill. 



Shell moderately compressed, with sixteen well-marked ribs ; valves nearly 

 equilateral, the right one less flat than the other; disk suborbicular, with small 

 subequal ears ; left valve with the ribs smooth and rounded on top, separated 

 by subequal, slightly channelled, smooth interspaces; the ribs on each side 

 just below the top are incised by a sharp, narrow groove, in which are closely 

 set small imbricated scales, which seem easily detached, so that in the worn 

 specimens the sulcus alone remains, ending in a narrow, sharp slit at the distal 

 end of the rib; the ears are flat, with sparse radial threads; in the right valve 

 the ribs are squarish and smooth, the sulci are absent, and the surface sculpt- 

 ure confined to faint incremental lines; the ears have a few imbricate radii, and 

 the notch is shallow ; the submargins are narrow and young shells have a 

 polished surface ; the internal surface is channelled in harmony with the ex- 

 ternal ribbing ; the auricular and cardinal crura moderately developed. Alt. 

 31, lat. 30, diam. about 6 mm. 



In young shells the sulci on the ribs are not conspicuous, and in perfect 

 ones the scales must more or less completely hide the grooves. 



Pecten (Chlamys) anguillensis Guppy. 

 /',;/,>! nii^iii//i-ii.ti.'i Guppy, 1'roc. Sri. Soc. Trinidad, Dec., 1867, p. 175. 



Oligocene of Anguilla and Antigua ; Guppy and Spencer. 



This is quite closely related to the recent P. antillarnm Recluz, of which 

 it is evidently the precursor, and also resembles /'. luciilciitiis Reeve. 



Pecten (Chlamys) ornatus Lamarck ? var. vaginulus Dall. 

 Oligocene of the Bowden beds, Jamaica ; Henderson and Simpson. 

 Seven small valves of a species closely resembling P. ornatiis were 



