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1471 



TERTIARY FAUN'A OF FLORIDA 



their margins, though well developed on the fragment. It is not the young 

 of any known species and it is highly probable that its remarkable compression 

 is not materially altered in the adult. 



The most common Oligocene species is C. mississippiensis Conrad, 1847, 

 from the Vicksburgian. A shell described by Conrad under the name of 

 Gratelupiaf mactropsis was later referred by him to Crassatellites and identified 

 by Gabb with an Oligocene species from St. Domingo and Costa Rica, which 

 Gabb had named C. Reevei. It is uncertain whether Conrad's -shell, which 

 came from Gatun, on the Isthmus of Darien, was from the Eocene shales or 

 the Oligocene sandstones of that locality, and I regard its identification with 

 C. Reevei as open to question. Gabb figures only a fragment. The following 

 are known from the Oligocene of Florida : 



Crassatellites (Scambula) deformis Heilprin. 

 Crassatella deformis Heilprin, Trans. Wagner Inst, i., p. 117, pi. xvi., fig. 63, 1887. 



Oligocene of the silex beds at Ballast Point, Tampa Bay, Florida; Dall 

 and Willcox. 



This species has the umbones notably flattened and is recognizable at once 

 by its strong, concentric undulations over most of the shell, but having the 

 posterior dorsal area unsculptured and the lunule and escutcheon deeply im- 

 pressed. The scar of the resilium is unusually narrow and the third right 

 cardinal nearly intact. 



Crassatellites (Scambula) jamaicensis n. s. 



PLATE 49, FIGURE 13. 

 Crassatella marylandica Guppy, Proc. U. S. Nat. Mus., xix., No. mo, p. 329, 1896; not 



of Conrad, 1838. 



Oligocene marl of Bowden, Jamaica ; Vendryes, Henderson, and Simpson. 



Shell solid, nearly equilateral, subtrigonal, rounded below and in front with 

 the posterior end obliquely subtruncate and a feeble carina bounding the pos- 

 terior dorsal area; lunule and escutcheon subequal, moderately impressed; 

 nepionic shell flattened, with seven or eight concentric low undulations, which 

 extend down about one-fourth of the way to the basal margin mesially, and 

 on the anterior slope are continuous, though the greater part of the disk and 

 the whole of the posterior dorsal area are smooth except for incremental lines ; 

 hinge normal, the posterior right cardinal nearly obliterated ; laminar grooves 

 deep ; internal margins of the valves smooth. Lon. 49, alt. 37, diam. 20 mm. 



