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1087 



TERTIARY FAUNA OF FLORIDA 



Shell small, siiborbicular, inflated, nearly equilateral, the posterior end 

 slightly more attenuated and produced ; beaks full but not high ; sculptured 

 with twenty-five ribs having in section the form of a truncated pyramid, sepa- 

 rated by narrower channelled interspaces, elegantly concentrically closely 

 striated; the anterior ten ribs bear A -shaped projections, the anterior wing of 

 the A being broad and produced, the posterior narrow and appressed; the 

 four ribs next posterior have on their tops slender arcuate transverse rather 

 sparse imbrications ; behind these the projections shift to the posterior side 

 of the summits of the ribs, gradually becoming more oblique, losing the an- 

 terior wing of the arch, and finally appearing as delicate spinules nearly 

 parallel with the ribs ; interior margin behind strongly serrate, below and 

 in front fluted, the flutings continued to the umbonal cavity as shallow sulci ; 

 hinge normal, delicate; a narrow, smooth area between the most anterior rib 

 and the hinge-margin. Alt. 15, Ion. 15.5, diam. 10 mm. 



This little species appears to be rather abundant in the sands. 



Cardium (Trachycardium) malacum n. sp. 



Plate 48, Figure 4. 



Oligocene sands of Oak Grove, Santa Rosa County, Florida. 



Shell small, solid, somewhat oblique, the upper anterior and lower posterior 

 margins produced, beaks small and low ; sculpture of thirty-two rounded- 

 triangular rather high ribs with very narrow channelled interspaces, which, 

 with the sides of the ribs, are concentrically striated; the first twelve ribs 

 have cup-like imbrications of the strung-convolvulus type, behind which they 

 change by the modification of the anterior part to 7-shaped, and finally to the 

 usual transverse oblique nodulous type; interior margin sharply and deeply 

 fluted, the channels continued half-way up the disk, the upper posterior margin 

 with seven or eight serrations. Alt. 24, Ion. 24, diam. 16 mm. 



This species has a peculiar obliquity that I have not elsewhere noticed, 

 otherwise its characters are not striking. 



Cardium (Trachycardium) var? bowdenense Dall. 



Cardium muricatum Guppy, Geol. Mag.. Dec. ii., vol. i., p. 4S0, 1874; not of Linne, 1758. 



This species from the Bowden marl and from the silex beds at Ballast 

 Point, Tampa Bay, Florida, was identified with the" recent muricatum by 

 Guppy. It has about the same number of ribs (thirty-seven to forty-one) 

 and the sculpture is much the same in character, but the similarities are all 



