ETJLIMA. 



153 



valve, equilateral, closed. Hinge with a single erect tooth closing 

 between two small diverging ones in the opposite valve : lateral 



- teeth none. Ligament internal. E. nitens. Turt. Mya. nitens, 

 Auct." PL xxiv. fig. 497. 



EETCIJSTA. Lam. Fam. Mactracea, Lam. Conchacea, Bl. — 



' Descr. Ovate or triangular, transverse, equivalve, inequilateral, 

 smooth ; hinge with a ligamentary pit, two diverging cardinal 

 and two lateral teeth in each valve ; muscular impressions two 



• in each valve ; palleal impressions einuated. East and "West 

 Indies and Mediterranean. — Obs. This genus is distinguished 

 from Mactra and Lutraria by the cardinal teeth being placed 

 one on each side of the ligamentiferous pit ; whereas in^the last 

 named genera they are both placed on the anterior side. E, 

 Plebeja. PI. iv. fig. 86. 



ESCTJTCHEOIS'. The impression on the posterior dorsal margin 

 of some bivalve shells. That on the anterior margin is named 

 the lunule. The escutcheon is pointed out by the letter e in 

 some of the figures of Cytherese. Fig. 117, a. b. e. 



ETHEEIA. Lam. 1808. Fam. Chamacea, Lam. and Bl. — Descr. 

 Irregular, inequivalve, inequilateral, foliaceous, pearly within, 

 covered by an olive green epidermis without ; hinge callous, un- 

 dulated, destitute of teeth ; Hgament partly external, partly 

 internal, passing through the hinge on a somewhat raised, callous 

 area in the lower valve. Muscular impressions elongated, two 

 in each valve, united by a slender palleal impression. Eivers of 

 Africa. — 05s. The irregular, unequal air-bubbles of the inner 

 surface, whence this genus derives its name, are very brilliant in 

 some species, and atone, in some measure, for the rugged 

 ugliness of the exterior. In its irregular form, foHated structure, 

 and toothless hinge, it resembles Osteea^ from which it differs in 

 having two muscular impressions. E. semilunata. PI. ix. fig. 155. 



EULIMA. Eisso, 1826. Fam. Scalareins, Lam. — Descr. Elon- 

 gated, smooth, pyramidal ; spire long, composed of numerous 

 whorls ; apex acute, slightly tortuous ; aperture oval, rounded 

 anteriorly, acute at the posterior union with the body whorl ; 

 outer lip slightly thickened ; columella smooth. Eig. 347, E. 



