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127Q 



TERTIARY FAUNA OF FLORIDA ' * 



This is a very distinct species, rounded trigonal when young; the older 

 specimens grow faster ventral ly than distally, making the form high and 

 short; the surface is covered with fine concentric threads close set, and has in 

 the middle of the disk a few faint undulations. The deep and prominent 

 undulations visible on many of the casts taken from the rock seem to be due 

 to erosion or decay before fossilization ; the lunule is cordate and sharply 

 limited by an incised line. The beaks rise high above the hinge, which is 

 normal with a well-developed anterior lateral. The margin of the valves forms 

 a subcircular outline, minutely crenulate. A well-grown specimen measures, 

 length 1 8, height 21, diameter 18 mm. 



Cytherea (Artena) staminea Conrad. 



Cytherea staminea Conrad, Fos. Medial Tert, cover of No. I, 1839, pi. xxi., fig. i. 

 Artena staminea Conrad, Am. Journ. Conch., vi., p. 76, 1870; not of Heilprin, Trans. 



Wagner Inst., i., p. 120, 1887. 

 Venus staminea Conrad, Bull. Nat. Inst., ii., p. 183, 1842; not of Conrad, Journ. Acad. 



Nat. Sci. Phila., vii., p. 250, pi. xix., fig. 14, 1837 ( =Protothaca sp.). 



Miocene of Calvert Cliffs, Plum Point, St. Mary's River, and other localities 

 in Maryland. 



A characteristic Miocene shell, notable for its inflated form and sharp, re- 

 curved, concentric ribs. The escutcheon is very large and bounded on each 

 side by a strong radial keel. 



Other species which have been referred to the genus Cytherea are C. ele- 

 vata H. C. Lea, 1845, from tne Miocene of Petersburg, Virginia, a minute shell 

 less than eight millimetres long; another C. elevata from the Miocene of 

 Florida was listed by Conrad in 1846, but not described or figured. C. missis- 

 sippiensis Conrad, from the Vicksburgian, was afterwards referred by him to 

 Chione. C. nuciformis Heilprin is a species of Chione. C. semipunctata, fig- 

 ured and named, but not described, by Conrad, from the Vicksburgian in 1848, 

 does not appear elsewhere, as far as I can discover, in the literature. C. sobrina 

 Conrad from the same horizon is a Chionella. C. multicostata Sby. has been 

 enumerated as one of the reef Pleistocene fossils of St. Domingo, but doubtless 

 through a misidentification, perhaps of C. Listen Gray, which is known to 

 occur in these beds. Callista acuticostata and C. Tryoniana Gabb, 1873, from 

 the Oligocene of St. Domingo, are referred by Guppy to C. circinata Born. 

 Caryatis Lordleyi Gabb, 1881, from the Pliocene of Costa Rica, is unfigured. 

 The C. Guppyana described at the same time is perhaps a Chionella. 



