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7IQ 



TERTIARY FAUNA OF FLORIDA 



This species when young is more ovate, when adult orbicular. The um- 

 bones are smooth, by which it may be instantly distinguished from P. (Aitni- 

 sitti/t) Lyoni. Whether it can be separated from Atmisiiii/i Morloni Rav. or 

 not will depend upon comparisons for which the material at my command is 

 as yet insufficient. The species is still living in Antillean and Gulf waters. 

 Alt. 50, lat. 55 mm. 



Amusium Lyoni Gabb. 

 I'll -iiroiu-i tia Lyoni Gabb, Journ. Acad. Nat. Sci. Phila., 2d Ser., viii., p. 347, pi. 45, tig. 



'2$n-l>, 1881. 

 J'ccttii Morlt'iti Guppy, <>/>. tit., p. 451, 1874. 



Oligoccnc of Anguilla, Guppy ; of Bowdcn, Jamaica, Guppy ; Pliocene 

 of Tehuantepec, Spencer; and of Costa Rica, Gabb. 



This form, otherwise very similar, is immediately distinguishable from P. 

 (A.) papyraccus by the nepionic sculpture of the umbonal region. 



Most of the recent Pectinidce of the Gulf and Antillean region are found 

 associated with other recent shells in the raised beaches and reefs so numer- 

 ous on the islands. It is not necessary to enumerate them here, but I may 

 mention that Pecten (Envola) ziczac L. is quite abundant in the Pleistocene of 

 Barbados. 



FOSSIL I'ECTENS OF THE FLORIDIAN REGION. 



The environs being now cleared, we may proceed to consider the species 

 represented in the Floridian horizons and the adjacent portions of the south- 

 eastern United States. 



Pecten (Pecten) Poulsoni Morton. 



/<v/<v/ *|>. Lcsticiir, Walnut Hills Kos., pi. 5, figs. 3, 4, 1829. 

 /'<</<;; /'on/mini Morton, Syn. Org. Rem., p. 59, pi. xix., fig. 2, 1834. 

 J\\/i'n clixatus Conrad, 1'roc. Acad. Nat. Sci., ii., p. 174, 1846. 

 Janira promens de Gregorio, Mon. Claib., p. 181, pi. 21, figs. 17-25, 1890. 



Oligocene (Vicksburgian) at Vicksburg, Carson's Creek, Wayne County, 

 and Shubuta, Mississippi ; near Rosefield, Louisiana, Vaughan ; near Archer, 

 Florida, Dall ; at Jarvcs Spring, Florida, Willcox. Abundant in the Vicks- 

 burgian beds generally, but hitherto frequently confused with P. pcrplanus 

 Morton. 



This is a very solid and characteristic little shell. The ribs in young 

 specimens are often simple; in adults they are apt to take on two or three 

 longitudinal grooves. The crura are strong and well developed. 



