EMARGINUIA. 143 



ELISMA. Lcacli. A sub-genus of Bulinus. B. acutus, Auct. Gray, 

 Turton, p. 185. 



ELLIPSOLITHES. Montf. (EXke^tg, ellipsis, oval ; Xidog, Uthos, 

 stone.) A genus composed of Ammonites, which instead of being 

 regularly orbicular, take an elliptical or oval form. This cha- 

 racter appears to be accidental, as some individuals of the same 

 species, both of Nautilus and Ammonites, are round, while others 

 are compressed into an oval form. 



ELLIPSOSTOMATA. Bl. (E\\ £ i^i £ , ellipsis, oyhI; areola, mouth.) 

 The third family of the class Asiphonibranchiata, Bl. The shells 

 of this family are described as of various forms, generally smooth ; 

 the aperture longitudinally or transversely oval, completely closed 

 by a horny or shelly operculum. This family contains the genera 

 Rissoa, Phasianella, Ampullaria, Helicina, and Pleuroceras. 



ELLIPTICAL. (EMa+ts, ellipsis.) Oval. Applied to any shell 

 or part of a shell, having that form. 



ELMINEUS. Leach. Order, Sessile Cirripedes, Lam. — Descr. 

 Four unequal valves, arranged circularly side by side, forming a 

 quadrate cone ; aperture large, sub-quadrate, irregular ; oper- 

 culum composed of four valves, in pairs. — Obs. This genus differs 

 from Conia in the structure of the shell, the latter being porous. 

 Fig. 22, Elmineus Leachii. 



ELPHIDIUM. Montf. (Conch. Syst. t. 1. p. 15.) A genus of 

 microscopic Foraminifera. 



EMARGINATED. (e, out ; margo, border.) Notched or hollowed 

 out. Applied to the edges or margins of shells, when instead of 

 being level they are hollowed out, as the outer lip of Oliva, fig. 

 457, at the base, and the ventral margins of some bivalves. 



EMARGINULA. Lam. (e, out ; margo, border.) Fam. Calyp- 

 tracea, Lam. Branchifera, Bl. — Descr. Patelliform, oblong or 

 oval ; anterior margin notched or emarginated ; apex posteriorly 

 inclined; muscular impressions wide. — Obs. Emarginula elon- 

 gata, of some Authors, Parmophortjs of De Blainville is com- 

 monly called the Duck's bill limpet, from its shape. The 

 Emarginulae may be known from Patellae and other neighbouring 



