TRANSACTIONS OF WAGNER 



1528 



TERTIARY FAUNA OF FLORIDA 



in his monograph of the Claiborne fauna. It is an internal cast and has not 

 much the aspect of a Thracia. It has, however, concentric ripples, and may 

 represent a tendency towards Cyathodonta on the part of some Eocene form. 



FAMILY PERIPLOMATIDyE. 



Genus PBRIPLOMA Schumacher. 



Corbula (sp.) Bruguiere, Encycl. Meth., livr. ii., pi. ccxxx., figs. 6a-6b, 1797. 

 Periploma Schumacher, Essai, p. 115, 1817, type P. incequivalvis Schum., = Anatina 



trapezoides Lam. ; Rang, Man., p. 325, 1829. 

 Osteodesma A, Blainville, Man. de Mai., ii., p. 660, 1827; A. trapezoides Lam. 



Subgenus COCHLOOESMA Couthouy. 

 Ligula (sp.) Montagu, Test. Brit. Suppl., p. 96, 1808 (Mya pr&tenuis Pult.) ; Brown, 



111. Conch. Gt. Brit., expl. pi. xiv., figs. I, 2, 1827; Zool. Textb. i., p. 461, 1832; 111. 



Conch. Gt. Brit., ed. ii., p. 106, 1844; not Ligula Bloch, Vermes, 1781. 

 Cochlodesma Couthouy, Boston Journ. Nat. Hist., ii., p. 170, 1839, type Anatina Leana 



Conrad ; Gray, Ann. Mag. N. Hist., ii., p. 25, 1840. 

 Bontaa (Leach MS.) Brown, 111. Conch. Gt. Brit., 2d ed., p. 106, 1844; in synonymy of 



Ligula prcetenuis Brown; Gray, List. British An., Moll., p. 70, 1851. 

 Bontia Gray, P. Z. S., 1847, p. 190; Herrmannsen, Ind. Gen. Mai., Suppl., p. 17, 1852. 

 Galaxura Leach, Moll. Gt. Brit., p. 271, 1852; Mya praztcnuis Pult. 

 ?Calcar<za Recluz, Act. Soc. Lin. de Bordeaux, xxvii., p. 47, 1869 ; not Calcarius Bechst., 



1802. 



Osteodesma (Deshayes MS.) Blainville, included several incongruous 

 forms, but Blainville mentions as the type Anatina myalis Lam., which is a 

 typical Thracia, and therefore the name cannot be conserved. 



The genus and its subdivisions show a gradual modification of the hinge- 

 characters. In Periploma there is a strong, prominent clavicular rib support- 

 ing the chondrophore, and in front of the latter is a small, lunate lithodesma ; 

 in Cochlodesma the clavicle is obsolescent and in front of the chondrophores 

 there is a cartilaginous mass of dark-brown color, uniting the valves and 

 occupying the place of the lithodesma, but uncalcified. In the European form, 

 Bontcea, the clavicle is non-existent, but a minute lithodesma still remains. 



Periploma Collardi Harris. 



Periploma Collardi Harris, Proc. Acad. Nat. Sci. Phila. for 1895, p. 52, pi. iii., fig. 4. 

 f Anatina claibornensis Lea, Contr. Geol., p. 40, pi. i., fig. 8, 1833. 



TPeriploma claibornensis Conrad, Am. Journ. Conch., i., p. 3, 1865 ; Checkl. Eocene Fos. 

 N. Am., p. 34, 1866. 



