FREE INSTITUTE OF SCIENCE 



989 



1 TERTIARY FAUNA OF FLORIDA 



lina, of Darlington District, South Carolina ; Pliocene of the Waccamaw 

 River, South Carolina, at Mrs. Purd^-'s marl bed ; C. W. Johnson. 



This species is of moderate size, rather compressed, with concentric waves 

 separated by equal or wider interspaces ; the waves vary from sharp edged to 

 flattened ; there is fine concentric and radial striation, feebler orr a marked 

 posterior fold and somewhat compressed, well-sculptured beaks. Conrad's 

 Abra Hohnesii was founded on Tuomey and Holmes's figure, but I am unable 

 to see any discriminating characters either in specimens or figures. The 

 figured specimen in the present work is from Oak Grove, and is chai'acterized 

 by a somewhat more elongated form and more uniform and close-set sculp- 

 ture, especially over the posterior dorsal area. The size of those collected is 

 also smaller than that of the full-grown Miocene specimens. It may perhaps 

 be separated from the type as a variety compacta. 



Besides the above, the following species are known from the Miocene and 

 later horizons. 



Semele Burnsii Whitfield. 

 Amphidesma Burnsii Whitfield. Mio. Moll. N. J., p. 79, pi. xiv.. figs. 16-18, 1894. 

 Ahra aqualis Whitfield, op. cit., p. 80, pi. xiv., figs. ii-iS, 1894; not of Say. 



Miocene marl of Cumberland County, New Jersey, at Shiloh and Jericho; 

 Burns. 



This is a small, nearly smooth species, with irregular incremental lines. It 

 has a rather inflated shell. An examination of Whitfield's types in the National 

 Museum shows that his Amphidesma Burnsii was founded on an imperfect 

 specimen of the same species as that which he had identified as Ahra aqualis 

 Say, but which is not Say's shell, nor an Abra. The other specific name must 

 therefore be retained for this shell, which is clearly distinct from the other 

 Miocene Semeles. 



Semele alumensis n. sp. 

 Plate 43, Figure 4. 



Miocene of the upper bed at Alum Bluff, Calhoun County, Florida ; Dall 

 and Burns. 



Shell small, moderately convex, but more compressed near the posterior 

 end ; anterior end slightly longer, rounded ; posterior end sloping above, with 

 a well-marked radial fold, especially in the left valve, subtruncate obliquely, 

 near the base, behind; sculpture of ten or twelve prominent, rounded con- 

 centric riblets separated by equal or wider interspaces, not very regularly dis- 

 posed ; the ribs tend to be especially prominent in the middle of the disk and 



