98 CONCHOLOGY. 



muscular impression large, elongated oval, slightly open in 

 front. 



Parmophora Australis. Parmophora brevicula. 



P. granulata. 



P. Australis. The Australian Parmophorus. 



Shell oblong, depressed ; vertex slightly recurved ; stri- 

 ated concentrically ; one margin rounded, and the other trun- 

 cated. 



2. Emarginula. The Slit Limpet. Four species. 

 Most of the shells of this genus are small ; some are ele- 

 vated, and others of a widely-depressed conical form. 



Shell conical, recurved ; summit entire; slit, or more or 

 less hollowed on the anterior side ; a muscular impression in 

 form of a horseshoe, open behind and thicker at the begin- 

 ning. 



Emarginula Blainvillii. Emarginula fissura. 



E. marginata. E. rubra. 



E. Blainvillii. Blainville's Emarginula. 

 Shell with the notch or slit in the middle of the back, and 

 not extending to the margin. 



E. fissura. The slit Emarginula. PI. 32, fig. 5. 



Oval, compressed, summit well marked, with reticulated 

 striae and ribs ; fissure extending half way from the margin 

 to the summit ; exterior light brown, interior white. 



E. marginata. The marginated Emarginula. 

 More compressed than the preceding ; summit distinct, 

 anterior margin formed like a gutter. 



3. Fissurella. The Keyhole Limpet. Nineteen species. 

 The perforation not being perfectly round, but generally 

 ovate oblong, procured for this genus its common name, by 

 which it is easily distinguished. 



Shell simple, conical, depressed, recurved ; summit perfo- 

 rated a little anterior in an oblong or oval manner, like a key- 



