EMARGINULA. 4i 
Ancillaria, by authors. They differ from the present genus 
Eburna in having the sutures of the spire covered with a polished 
enamel, A. glabrata, fig. 455. The Eburne resemble the 
Buccina in some respects, but a glance at the figure will enable 
the reader to distinguish a true Eburna from all other shells. 
Fig. 426, Eburna Zeylanica. 
E’'GEON. Montf. A genus of microscopic Foraminifera. 
EGERTA. Lea. (Contrib. to Geol. p. 49. pl. 1.) A genus of 
fossil bivalves, described as very variable in form, with or with- 
out lateral teeth, sometimes a crenated margin, &ce. The only 
certain characters appear to be that they have two diverging 
cardinal teeth in each valve, one of which is bifid, and an ex- 
ternal ligament. lea states that the Egerie should be placed 
between Sanguinolaria and Psammobia, which two latter genera 
have been united by Sowerby. Fig. 103, E. Triangulata, from 
the tertiary formation of Alabama. 
ELLIPSOLITHES. Montf. (Erenpus, ellipsis, oval; dos, lithos, 
stone.) A genus composed of Ammonites, which instead of 
' _ being regularly orbicular, take an elliptical or oval form. 
ELLIPSOSTOM'ATA. BI. (E\cuis, ellipsis; orapa, mouth. ) 
The third family of the class Asiphonibranchiata, Bl. containing 
the genera Rissoa, Phasianella, Ampullaria, Helicina, and Pleu- 
roceras. 
ELLIPTICAL. (Pcs, ellipsis.) Expresses the form of the plane 
produced by an oblique section of a cone,i. e. 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; opercu- 
lum, composed of four valvesin pairs. Obs. This genus differs 
from Conia in the structure of the shell, the latter being porous. 
Fig. 22, Elmineus Leachii. 
ELPHI’DIUM. Montf. A genus of microscopic Foraminifera. 
EMARGINATED. (e, out; margo, edge or 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. 
EMARGIN'ULA. Lam. (e, out; margo, border.) Fam. Calyp- 
traciens, Lam. JBranchifera, Bl. Descr. Patelliform, oblong 
or oval; anterior margin, notched or emarginated; apex poste- 
tiorly inclined; muscular impression wide. Obs. Parmophorus 
Bl. fig. 242, E. Elongata, Auct. is commonly called the 
Duck’s Bill Limpet, from its singular resemblance to that organ. 
The Emarginulz may be known from Patellee and other neigh- 
bouring genera, by the notch or slit in the anterior edge. In 
Rimula, Def. fig. 243, this slit is near the apex, and does not 
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