96 PEOVISIONAL AID TO THE STUDY OP TASMANIAN MOLLUSCA- 



Genus Schismope. Jeffreys. (391.) 

 Shell minute, thin, translucent, not pearly, spire laterally- 

 compressed, as in Stomatia ; slit of the young shell is 

 converted into a foramen in the adult; it does not 

 commence until the animal is half grown. Dist, — 

 Mediterranean, Japan, Tasmania. 



(xlviii.) Family Haliotid^e. 

 Genus Haliotis. Linn. (392-395.) 

 Shell ear-shaped, large, with a small flat spire ; aperture very 

 wide, iridescent; exterior striated, dull; outer angle 

 perforated by a series of holes, those of the spire 

 progressively closed. Dist. — Almost world-wide. 



(xlix.) Family Fissueellid^;. 

 Shell conical, limpet -shaped; apex recurved; nucleus spiral, 

 often disappearing in the course of growth ; anterior 

 margin notched ox apex perforated; muscular impression 

 horse-shoe shaped, open in front. 



Genus Fissueella. Lam. (396-401.) 

 Shell oval, conical, depressed, with the apex in front of the 

 centre, and perforated; surface radiated or cancellated ; 



muscular impression with the points incurved. Dist. 



Universal, but mostly in warm seas. 



Sub-Genus Maceoschisma. Swainson. 

 Shell square, oval, roughly rayed, truncate at the end ; perfora- 

 tion very large, sub-triangular, elongated. 

 Genus Emaeginula. Lam. (402-405.) 

 Shell oval, conical, elevated, with the apex recurved; surface 

 cancellated; anterior marginnotched; muscular impression 

 with recurved points. Dist.— Almost world-wide, 

 range low-water to 90 fathoms. 



Genus Pabmophoeus. Blainv. (406-408.) 

 lengthened oblong depressed; apex posterior ; front margin 

 incurved ; muscular impression horse-shoe shaped, 

 elongated ; shell smooth, white. Dist. — East Indies, 

 Philippines", Australasia. 



Shell 



(1.) Family Patellum:. 

 Shell wholly external, disc shaped, with apex anteriorly 

 directed. (Limpets^) 



Genus Acm^a. Esch. (409-417.) 

 Shell solid, limpet form ; apex erect, or anteriorly inclined. 

 Dist. — Mostly West Coast of North America, Europe, 

 Australasia. 



