252 EOCENE MOLLUSCA. 
Size.—Axis, 8-12ths of an inch; diameter, 3-12ths of an inch. 
Locality —Alum Bay (Stratum No. 29, Prestwich ?); rare. 
No. 173. Pxievroroma pitinum. F. H. Edwards. Tab. XXVIIL fig. 15, a, 4. 
P. testé minima, oblonga, fusiformi, granulatd, concentrice lineatd: spird obtusius- 
culd, sub-conicd: anfractibus sub-convevis, duplici serie granulorum coronatis, spatio 
rater series concavo, levi; ultimo anfractu antice valde coarctato, in canalem latis- 
simum, brevem, reflerum producto ; lineis spiralibus, acutis, sub-distantibus : apertura ovali; 
labro acuto, leviter arcuato, intis plicato; sinu latissimo, mediocriter profundo, sub- 
trigono, anticad in margine collocato. 
Shell very small, oblong, fusiform, spirally girt by a double row of small, bead-like 
tubercles, concentrically lined; spire rather thick, nearly conical; whorls slightly 
convex ; the posterior margins concave, smooth, bordered in front and behind by the 
rows of tubercles; the last whorl much contracted in front, and terminating in a 
very wide, short, but distinct, canal, a little bent backwards ; the concentric lines 
thin, sharp, and rather distant. The aperture is of an oval form; the outer lip 
slightly arched, expanding towards the front, sharp-edged, and plicated within; the 
sinus very wide, moderately deep, somewhat triangular in shape, and placed in the 
front part of the posterior margin. 
This Pleurotoma is allied to P. microcheila, the var. producta of which closely 
resembles it; but the wide posterior margins, the greater regularity of the granula- 
tions, and the broad anterior canal, distinguish the present species. 
Size.—Axis, not quite 3-12ths of an inch ; diameter, 1-1! 2th of an inch. 
Locahty.—Alum Bay (No. 29, Prestwich). 
No. 174. Prteurotoma tricincta. F. #. Edwards. Tab. XXVIII, fig. 6, a, 3. 
P. testé parva, elongato-fusiformi, sub-turritd, spiraliter lineatd: spird acuminata, 
breviusculd, aperluram in longitudine vie equanti: aufractibus depresso-convewis ; postice 
profunde canaliculatis, marginatis ; ultimo anfractu in canalem brevem, latum, producto ; 
Tineis spiralibus ewilibus, filiformibus, irregularibus, sub-clathratis: aperturd oblongo- 
ovali ; labro arcuato ; sinu lato, mediocriter profundo, in margine collocato. 
Shell small, oblong, fusiform, indistinctly turreted, concentrically lined; spire 
pointed, rather short, not equalling the last whorl in length ; whorls flatly convex at 
the sides; the posterior margins deeply hollowed, giving the turreted aspect to the 
spire, and ornamented with a series of roundedly curved plications, formed by the 
successive elevated margins of the sinus; the sutural edge is bordered by a sharp, 
ridge-like, raised line ; the last whorl is contracted in front, and terminates in a very 
