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TERTIARY FAUNA OF FLORIDA 



by sharp, narrow, arcuate Amoves in such a way as to produce the effect of a 

 parting on the periphery of the valve. This grooved and faceted sculpture 

 ceases abruptly behind, but the rows of facets are continued as wider longi- 

 tudinal riblcts posteriorly. The umbonal reflection is heavy and radially 

 striate ; the apophysis seems to have been obsolete and its remains appressed 

 to the internal arch of the umbo. The whole is rather thick and solid, and 

 the antero-postcrior length of the fragment is six and a half millimetres. 



The very distinct sculpture of this shell instantly distinguishes it from 

 any other known Teredina. 



The only other Pholads of which I find any mention in our Tertiary liter- 

 ature arc /-*. ovalis Say, which may be a Fistnlana, and will be later referred 

 to under that head; and Pliolas petrosa Conrad (Bull. Nat'l Inst, ii., p. 193, 

 pi. 2, fig. 4, 1842 ; and Am. Journ. Sci., 2d Ser., i., p. 213, pi. 2, fig. I, 1846), 

 which is not a Pholad,* though externally much like one. 



Superfamily MYACEA. 

 FAMILY GASTROCH/ENID/E. 



C,i mis G-ASTROCH^3NA (Spengler) Cuvier. 

 (iiisfnii'/in-im Spender, Nova Acta Soc. Sci. Hafn., ii., p. 174, 1783; Desh., Traite de 



Conchy!., i., p. 26, 1844. 



^ Cliana Retains, Nov. Test. Gen., p. 19, 1788; Schum., Essai, p. 94, 1817. 

 -' Mytiliis ]5nigiiierc, Kncyc. Mcth., pi. 219, 1792. 

 < Fistiilana liosc, Hist. Nat. Coq., ii., p. 208, 1802. 

 Trapezium fl, M cleric, Entw., Neuen Syst. Schal., p. 69, 1811. 



(j<^ti-,h-/in-na Cuvier, Rcgne An., ii., p. 490, 1817 ; Lam., An. s. Vert., v., p. 446, 1818. 

 Koffllaria (Klcurian MS.) Blainv., Diet. Sci. Nat., vol. 57, p. 244, 1828 (G. modiolina 



Lam.); Tryon, Mon. Pholad., p. 39, 1862. 



Roxi-llariu Menkc, Syn., p. 121, 1830; Agassiz, Norn. Zool., 1845. 

 Gastrochana Fischer, Man. de Conchyl., p. 1128, 1887. 



* Phtnacomya n. g. Shell thin, feebly radially sculptured, pholadiform; more or less expanded 

 anil truncate anteriorly, adult with a narrow dorsal gape in front of the beaks, shell closed below, 

 equivalve; young with a wide anterior gape which is gradually closed with growth as shown by the 

 incremental lines; shell attenuated and smoother posteriorly. Type 1'lioladomya cantata Sowerby, 

 Desh., An. s. Vert. Bassin de I'.iris, i., p. 277, pi. ix., fig. 6-8, 1868. 



It is very doubtful if the group represented by this type has any very close relation to Phola- 

 tiomya. 



The American representatives are Pholas pflrosa Conrad, above cited, and Fhol,iJomya Mauryi 

 Harris, Hull. I'al., iv., p. Jl, pi. (>, fig. 17 a, 1896. All are Eocene and, so far as known, the 

 genus is Eocene only. 



