FISSURELLIDEA. 



287 



Family FISSURELLID.E. 



Genus FISSURELLIDEA, D'Orbigny. 



[Yoy. Ameriqiie Mcrkliouale, t. v. 1841, p. 477.] 



Shell oval, somewhat depressed, surface not rugose ; apical 

 perforation immense, ovate, subcentral, and having a thickened 

 border internally. 



Type. — Finsurellidea megatrema, D'Orbigny. 



Fissurellidea malleata, Tate. 



[Plate Vlir. Figs, ha-c] 



1882. Fissurellidea malleata, Tate, Trans. Roy. Soc. South Aust. vol. v. 



p. 46. 

 1893. Fissurellidea malleata, Tate and Dennant, id. vol. xvii. pt. 1, p. 223. 



Shell patelliform, ovate, contracted at one end ; surface 

 ornamented by conspicuous, concentric growth-lines and encircling 

 punctures, these latter being very small, close together, and 

 regular, each one being almost square ; border smooth ; apical 

 perforation oval, very large, thickly bordered internally ; interior 

 scored by encircling muscular attachments and roughened by 

 ridges radiating from the apical perforation. 



This species does not appear to have been figured hitherto. 



Dimensions. — Length 30 mm.; breadth 19 mm.; length of apical 

 perforation 7 mm. 



Form, and Loc. — Eocene : Muddy Creek, Victoria. 



G. 4225. Specimen in which the radiating ridges on the 

 interior are obsolete, and the apical perforation is relatively 

 broader than in the type. Presented hy John Dennant, Esq. 



G. 5539. Example of the adult, shell much thickened and 

 corrugated internally. Purchased. 



G. 9468. Example of the neanic stage of growth. Purchased. 



Fissurellidea, sp. 



G. 4226. Example of a new species, much rolled and too 

 imperfect for detailed description ; it is narrower than F. malleata. 

 From the Miocene (?) of Muddy Creek, Yictoria. 



Presented lij John Dennant, Esq. 



