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907 



TERTIARY FAUNA OF FLORIDA 



Labiosa (Raeta) canaliculata Say. 

 Lutraria canaHcuhita Say, Journ. Acad. Nat. Sci. Phila., ii., p. 310, 1821. 

 Macfra canaliculata ^^a^^, Conch. Icon., Mactra, fig. 122, 1854. 

 Mac fra campechcnsis Gra.y, Wood's Ind. Test. Suppl., fig. 3, 1828. 



Post Pliocene of South Carolina, Burns ; and of North Creek, Little 

 Sarasota Bay, Florida, Dall ; living from New Jersey southward to southern 

 Brazil, United States National Museum. 



I have not yet seen this species from the Pliocene, though it may very 

 likely be found in that formation in the future. The variations in outline and 

 especially in the recurvature of the rostrate end of the shell in the living 

 form are very remarkable. They seem to be purely individual. Notwith- 

 standing the fact that dead valves of this shell are found in windrows on the 

 beaches at some points of the southern coast, the character of the soft parts 

 is unknown, and I shall be very greatly obliged to any one who can furnish 

 me with a specimen of the animal in spirits in order that its systematic posi- 

 tion may be positively settled. 



Labiosa (Raeta) alta Conrad. 

 Plate 27, Figures 20, 23. 

 Raeta alta Conr., Kerr's Geol. Rep. N. Car., App., p. 19, pi. 3, fig. 3, 1875. 

 Raeta crecta Conr., ibid., p. 19, 1875. 



Newer Miocene of Goldsborough, North Carolina, Kerr ; and of the 

 York River, Virginia, near Yorktown, Harris and C. W. Johnson. 



This species is shorter and higher, with the beaks more erect and the 

 concentric undulations more feeble than in L. canaliadata. The chondrophore 

 is frequently quite large and in general proportionately larger than in the 

 recent species, but this character is variable and the two species founded by 

 Conrad on specimens of this shell from North Carolina and based on differ- 

 ences in the size of the cartilage-pit must be united under the name which 

 precedes the other and is illustrated by a figure. Figure 23, plate 27, rep- 

 resents the variation which received the name of erecta from Conrad. 



Family MESODESMATID^. 



This family, with a hinge formed on much the same plan as that of 

 Mactra, is sharply distinguished from the latter by its separate, free, and naked 

 retractile siphons, and also by a certain excessive solidity and thickness of its 

 valves relatively to their comparative dimensions. It is by this latter habit of 



