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1389 



TERTIARY FAUNA OF FLORIDA 



Divaricella prevaricata Guppy. 



Divaricella prevaricata Guppy, Proc. U. S. Nat. Mus., xix., p. 327, pi. xxx., fig. 4, 1896. 

 Oligocene of the Bowden marl, Jamaica. 

 Resembling D. quadrisulcata Orbigny but constantly smaller and weaker. 



Divaricella chipolana n. sp. 

 PLATE 51, FIGURE 2. 



Oligocene of the Chipola beds at the Chipola River and of the lower bed 

 at Alum Bluff on the Chattahoochee River ; upper Oligocene of the Oak Grove 

 sands, Oak Grove, Santa Rosa County, Florida, Burns ; Pliocene of the Bruns- 

 wick Canal, Georgia, and of the Caloosahatchie beds of Florida. 



Shell solid, subcircular, rounded in front and behind, equilateral, with in- 

 conspicuous beaks; sculpture of concentric incremental lines and an arcuate 

 excavated sculpture (common to the genus and somewhat variable in minor 

 detail in the species) as figured, and some obscure irregularly radial impres- 

 sions on the anterior slope; lunule in the right valve short, small, rather 

 broad ; in the left valve none or hardly any ; escutcheon none ; resting stages 

 variable, not conspicuous ; hinge with strong cardinals and faint traces of the 

 laterals, of which the right anterior lateral is best developed. Alt. 17, Ion. 19, 

 diam. 10 mm. 



This species is especially characterized by its lunule, by the rounded, not 

 angular, ends of the hinge-line, the absence of any denticulation of the mar- 

 gins due to the excavated sculpture, and the extremely fine crenulations of the 

 rather broad margins. 



Absent during the cold-water period of the Miocene, this form appears to 

 return with the warmer Pliocene waters, again to disappear finally with the 

 renewed cooling off of the waters in Pleistocene time. 



Divaricella quadrisulcata Orbigny. 

 PLATE 51, FIGURE i. 



Tellina divaricata Dillwyn, Cat. Rec. Sh., i., p. 102, 1817 (ex parte), and many other 

 authors. 



Lucina divaricata Lamarck, An. s. Vert., v., p. 541, 1818 (partim), and many other au- 

 thors, not of Linne; Say, Journ. Acad. Nat. Sci. Phila., p. 148, 1824; Conrad, 

 Fos. Medial Tert., p. 39, pi. xx., fig. 3, 1840 ; Am. Journ. Sci., 2d Sen, i., p. 404, 1846 ; 

 Gould, Inv. Mass., p. 70, 1841 ; Tuomey and Holmes, Pleioc. Fos. S. Car., p. 59, P 1 - 

 xvii., figs. 10-11, 1857; Emmons, Geol. Rep. N. Car., p. 291, 1858; Holmes, P.-P1. 

 Fos. S. Car., p. 27, pi. vi., fig i, 1860. 



