FREE INSTITUTE OF SCIENCE 



TERTIARY FAUNA OF FLORIDA ' ** 



and on the left valve the different individuals differ in the amount of their 

 radiation. 



Pecten (Hyalopecten) sp. indet. 



Lower Miocene of the Ashley River, South Carolina, in the so-called 

 " phosphate rock." 



Valves of a species too imperfect for satisfactory description, yet showing 

 distinctly a thin, undulated, and probably radially striate shell, of about the 

 size of half-grown /*. fragilis (circa eight millimetres in altitude), were found 

 in the rock above mentioned. The shells were crushed and their undulations 

 flattened down during fossilization, and the chief character which appears to 

 have distinguished them from P. fragilis is that the undulations were higher 

 and sharper and the form perhaps more ovate. Still, this group is so singular, 

 and its discovery in a fossil state so interesting, that I feel it should be 

 recorded. 



Pecten (Pseudamusium) Guppyi Dall. 

 PLATE 34, FIGURES 12, 13. 



This species has already been cited (p. 718) as occurring in the Alum 

 Bluff beds at Oak Grove, Santa Rosa County, Florida, as well as in the Oligo- 

 cene and later formations of the Antilles and Costa Rica. 



Subgenus AMUSIUM (Bolten) Schumacher. 



.\iiuiaiiint (Rumphius, 1705) Bolten, Mus. Bolt., ist ed., p. 165, 1798 (no description); 

 Sebum., Essai, p. 117, 1817 ; Dall, Bull. Mus. Comp. Zool., xii., No. 6, p. 207, 1886. 

 ricuroiifctM Swainson, Malac., p. 388, 1840. 

 Type Ostrcii plcuroncctcs Linnc. 



Pecten (Amusium) precursor n. s. 



Oligoccne of the Chipola beds at Alum Bluff and on the Chipola River 

 and elsewhere in these beds; Burns and Dall. 



There are several species of Ainitsiuiii ranging from the Oligocene to the 

 recent fauna in this region. In general they appear extremely similar, so 

 much so that such figures as "are ordinarily given would show no differential 

 characters. By careful and repeated study I find myself able to separate 

 them by the umbonal sculpture, which differs in the different forms as follows : 



Ncpionic shell perfectly smooth externally. 



1. Shell more or less ovate: P. pafyraccits Gabb. 



2. Shell very large, orbicular: P. Mortoni Rav. 



13 



