FREE INSTITUTE OF SCIENCE 



TERTIARY FAUNA OF FLORIDA 



Orassatellites (Scambula) melinus Conrad var. meridionalis Ball. 



PLATE 37, FIGURES 6, 13. 



Crassatella melina Conrad, Fos. Tert. Form., p. 23, pi. ix., fig. 2, 1832; Fos. Medial Tert, 

 p. 22, pi. xii., fig. 2, 1838; Whitfield, Mioc. Lam. N. J., p. 60, pi. viii., figs. 11-13, 

 1895; Ball, Trans. Wagner Inst, iii., part v., p. 1193, pi. xxxvii., figs. 6, 13, 1900. 



The type in the Miocene of Shiloh and Jericho, Cumberland County, New 

 Jersey; Plum Point, Maryland; the Eastern Shore of Virginia, and the 

 variety at Alum Bluff, Florida. 



The typical locality of the Crassatella melina was New Jersey, where it is 

 the most common bivalve in the marls. The variety, which I have been tempted 

 to call a species, differs from it in having the nepionic undulations continued 

 on a radius of twelve millimetres or more, while in melinus the radius of undu- 

 lation is not above seven millimetres ; the southern shell is relatively less com- 

 pressed; the anterior dorsal area is bounded by a ridge within which the im- 

 pressed lunule occupies about half the area, while in typical melinus the mar- 

 gin is coincident throughout with the ridges proceeding from the beaks. The 

 Florida shell is more attenuated behind, the dorsal slopes more steep, the margin 

 of the base more rounded in front and more insinuated behind. But Plum 

 Point specimens are to some extent intermediate between the two in some of 

 these characters, so I prefer to regard the Alum Bluff shell for the present as 

 a variety. 



Crassatellites (Scambula) marylandicus Conrad. 

 Crassatella marylandica Conrad, Fos. Tert. Form., p. 22, pi. viii., fig. I, 1832; Fos. Medial 



Tert, p. 21, pi. xii., fig. i, 1838. 

 f Crassatella turgidula Conrad, Fos. Medial Tert., p. 69, pi. xxxix., fig. 7, 1843. 



Miocene of the Choptank River, Maryland, Conrad ; of the Patuxent River 

 and Parker's Creek, Maryland, Burns and Harris. 



This species as regards form bears to C. turgidulus Conrad almost exactly 

 such a relation as C. melinus bears to the variety meridionalis. The nepionic 

 shell of C. marylandicus has three or four feeble concentric undulations com- 

 pressed into a radius of as many millimetres, while in C. turgidulus there are 

 five or six rapidly increasing reaching to a radius of about fifteen millimetres 

 but obsolete in front and behind. C. marylandicus has, like var. meridionalis, 

 a rostrate, turgid form and high beaks ; C. turgidulus, like C. melinus, com- 

 paratively low beaks, compressed or less turgid form, and broad posterior end. 

 If C. turgidula is allowed specific rank, it would seem that the same should be 

 accorded to the var. meridionalis. 



