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TERTIARY FAUNA OF FLORIDA -^ " 



the length ; umbones small, low, pointed, adjacent ; surface marked only with 

 lines of growth ; anterior end short, evenly rounded from the beaks to the 

 base ; posterior end long, dorsal slope nearly rectilinear, ending in a rounded 

 point; base rather arcuate ; dorsal areas and umbonal angle obscure or un- 

 defined; pallial sinus very wide and short; hinge feeble, the lateral laminEe 

 finely granulose or smooth, the posterior markedly longer than the anterior; 

 left cardinal with a well-marked posterior accessory lamella ; chondrophore 

 small and inconspicuous; hinge-plate very narrow. Lon. 27, alt. 14, diam. 

 10 mm. 



This is a very interesting and peculiar species. The figured specimen 

 is rather shorter and higher than that of which the dimensions are given 

 above. The young vary considerably in form from subtrigonal to quite 

 elongate, but these differences become less marked in the adult, though 

 not wholly eliminated. It is one of the most characteristic species of the 

 Caloosahatchie beds. 



Genus RANGrlA Destaotiliiis. 



Gnathodon (Gray) Sowerby, Gen. Shells No. 36, Dec, 1831. (Type G. cwieatus Gray) 



Dall, Mon. Gnath., Proc. U. S. Nat. Mus., xvii., p. 85, 1894. 

 Rangia Desmoulins, Actes Soc. Lin. de Bordeaux, v., No. 25, p. 50, Feb. 15, 1832. 

 Gnatodon Rang, Nouv. Ann. du Mus., iii., p. 217, 1834. 

 Columbia Blainville MS., Rang, op. cit., p. 217. 



CIathrodo7i (as of Gray MS.) Conrad, Am. Journ. Sci., xxiii., p. 340, 1833. 

 Pcrissodon Conrad, Proc. Acad.' Nat. Sci. Phila. 1862, p. 573. 

 Not Gnathodon Goldfuss, Man. Zool., 1820. 



The reader is referred to the writer's monograph above mentioned for 

 all details. Its Mactroid character and close relationship to Mtilinia is there 

 fully established. The synonymy js here finally rectified by the rejection of 

 GnatJiodon, which turns out to have been used by Goldfuss for a gd^ius of 

 fishes in 1820. 



In the monograph I mentioned that Gray received his specimens from 

 Canada, which he described (as stated by Conrad) under the name of Clathro- 

 don, and sent the MSS. to the American Journal of Science to be published 

 in America about 1830 ; also that the publication was not made. It is a 

 singular circumstance that immediately after reading the last proofs of my 

 paper on Gnathodon, while engaged in examining a miscellaneous lot of 

 papers from the library of the late Dr. Isaac Lea, presented to the Smith- 

 sonian Institution by his son-in-law, Dr. L. T. Chamberlain, I came upon a 



