PROSOBRANCHIATA. 185 
No. 121. Mirra porrecta. F. &. Edwards. Tab. XXIV, fig. 7 a—c. 
Mirra porrecra, Morris. 1854. Cat. Brit. Foss., 2d edit., p. 258. 
M. testé elongato-fusiformi, gracili, ad basin concentricé sulcatd, ceterum levi; spird 
porrecta : anfractibus depresso-convewis, unico sulco prope marginem suturalem circumdatis ; 
marginibus posticis simplicibus: apertura angustd, lineari ; labro acuto, intis crenulato ; 
columella quinquies plicata. 
Shell elongated, fusiform, slender; smooth, except at the base, where it is tra- 
versed by several broadish, obscure furrows; the spire elevated, nearly equalling the 
aperture in length; the volutions, seven or eight, flatly convex, with the posterior 
margins simple, and bordered by a deep furrow, which runs round the shell near the 
suture. The aperture is narrow, with nearly parallel margins ; the outer lip sharp- 
edged, and finely and regularly crenulated within; the columella presents five sharp 
folds, of which the anterior two are very oblique, and much smaller than the others. 
In the smooth surface, margined whorls, sharp outer lip, and columellar folds, this 
Mitra resembles AZ. marginata (Lamk.), from the Paris basin. It is, however, a much 
narrower and more slender shell; the margins of the whorls are without the crenu- 
lations which characterise that species, and the outer lip is finely crenulated within. 
The species appears to be perfectly distinct. 
Size.—Axis, 4-12ths of an inch; diameter, 1-8th of an inch. 
Localities—Barton, Bracklesham Bay. 
No. 122. Mirra opssa. F. 2. Edwards. Tab. XXIV, fig. 4 a—d. 
M. testa ovato-oblongd, ad basin concentrice sulcata, ceterum levi; spird acuminata, 
aperturam in longitudine vie equanti ; anfractibus convexiusculis, antice coarctatis, postice 
marginatis ; apertura elongato-ovali ; columella terties plicatd. 
An ovately oblong shell, smooth except at the base, where it is traversed by a few 
obscure furrows ; spire elevated, nearly as long as the aperture, and terminating in a 
small, pointed pullus, formed of two round, smooth, unequal volutions; the whorls, 
which are five in number, exclusive of the embryo, are flatly convex, and contract 
rather suddenly in front; the posterior margin is bordered by a shallow furrow, which 
runs round the suture, and the edge is depressed and flattened, giving somewhat of a 
turreted appearance to the spire. The aperture is ovate, moderately wide, and termi- 
nates in front in a short, wide canal, formed by the sudden contraction of the whorl ; 
the columella is nearly straight, and presents three oblique distant folds. 
The general form, the width and greater size of the shell, and the number of the 
