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603 

 TERTIARY FAUNA OF FLORIDA 



name P/ciirodontc, it will be necessary to adopt d'Orbigny's name of Nnadina 

 for the genus. 



Superfamily ARCACEA. 



Family PARALLELODONTID^. 



Genus CucuUsea Lamarck. 



Cucidlcea Lam., Syst. des. An., iSoi, p. 116; Bosc, Hist. Nat. Coq., iii., p. 121, 1802. 



Type C. (Area) concamerata Martini. 

 Idonearca Conrad, Proc. Acad. Nat. Sci., 2d Ser., vi., p. 289, 1862. Type /. tippana 



Conrad, Cretaceous. 

 Lcitiarca Conrad, op. cit., p. 289, 1862. Type CuctdlcBa gigantea Conr., Eocene. 



The only general difference between the recent type of Lamarck's genus 

 and the fossils named by Conrad, is that the fossil shells are thicker. For 

 some unknown reason Conrad regarded Latiarca as a subgenus of Trigo- 

 narca Conrad, which appears to be a valid and recognizable group, though 

 perhaps rather close to Trinacria. 



The genus Cucidlcea has not been reported from our Post-Eocene hori- 

 zons. Professor W. B. Clark* has discussed the type species with numerous 

 illustrations. I am inclined to believe that the Eocene of Virginia and Mary- 

 land affords two species of Cucidlma, C. gigantea Conr. (+ onocJiela Rogers) 

 and C. transversa Rogers. The latter appears in the Chickasawan (Suessonian) 

 Eocene at Gregg's Landing, Alabama, and may be what Harris (Bull. Pal. No. 

 4) has called C. Saffordi Gabb, which he reports from the Midway. Whether 

 this is correct or not, the Gregg's Landing shells agree exactly with Maryland 

 specimens of the same size. C. gigantea, abundant in Maryland, is not re- 

 corded authentically from the Gulf States. The differences between these two 

 forms is not confined to aged and young, but is equally marked between 

 adults, though C. gigantea, especially, is quite variable. C. macrodonta Whit- 

 field appears to be unknown in the northern Eocene, but is abundant in the 

 Lower Eocene of the Gulf States. Its most conspicuous characteristic is the 

 discrepancy between the sculpture of its two valves, which is often very 

 marked. The CucidlcBa levis Tuomey, from the Eocene of Wilmington, North 

 Carolina, has not been figured or sufficiently described, and must be regarded 

 as a doubtful species. 



I have retained Cucidlcea in a distinct family from Area, not because I 



*Bull. U. S. Geol. Survey, No. 141, p. 84, 1896. 



