TRANSACTIONS OF WAGNER 

 1184 



TERTIARY FAUNA OF FLORIDA 



Shell large, thin, concentrically striated, beaks small, not elevated ; anterior 

 end short, rounded, posterior end longer, larger, more arcuate above, the lower 

 portion near the base produced ; groove for the ligament very narrow ; hinge- 

 plate narrow, slightly excavated ; teeth and adductors normal ; margin simple. 

 Alt. 27, lat. 26, diam. 12.5 mm. 



The specimen figured from the silex beds being defective at the posterior 

 margin, a much finer specimen from the Chipola beds, subsequently acquired, 

 has been figured to show the normal form of the species. A form from the 

 sands at Oak Grove seems to be the same, but differs by the presence of a 

 minute lunule or incised line in front of the beaks as in Sphcerella, the adductor 

 scars, however, are normal. As the Oak Grove specimens are all young, I 

 prefer to regard them as a variety of D. alta until more information is available. 



Diplodonta radiata n. sp. 

 PLATE 44, FIGURE u. 



Oligocene sands of Oak Grove, Santa Rosa County, Florida; Bums. 



Shell large, very thin, finely concentrically sculptured with minutely 

 wrinkled silky striae ; anterior end shorter and narrower, slightly produced 

 below, posterior end wider, rounded ; hinge-plate narrow, channelled in front, 

 cardinals small, short, normal ; ligamentary groove very short, beaks low, 

 inconspicuous ; adductor scars and pallial line normal ; pallial area smooth, 

 with, towards the base, numerous obscure lira which appear on the basal margin 

 as short elevated lines with abrupt terminations, somewhat as in Propeamusium. 

 Alt. 18, lat. 20, diam. 10 mm. 



This is a peculiar species and, so far as the lira? are concerned, appears to 

 be unique. They are entirely distinct from the radiating striae not uncommon 

 on the pallial area of Lucinoid bivalves, being most elevated at their distal 

 termination, and found in both the young and mature shells. 



Diplodonta shilohensis Dall. 



Mysia parilis Conrad, Am. Journ. Conch., ii., p. 71, pi. 4, fig. I, 1866; Whitfield, Mio. 



Moll. N. J., p. 61, pi. 9, figs. 9-13, 1895. 

 Not Mysia parilis Conr., Journ. Acad. Nat. Sci. Phila., 2d Ser., iv., p. 278, pi. 46, fig. 16, 



1860; nor Mysia parilis Conr., Am. Journ. Conch., i., p. 153, 1865. 



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

 Conrad and Burns. 



The nomenclature of this species illustrates one of the peculiarities of Con- 



