298 EOCENE MOLLUSCA. 
No. 222. Pxrevrotoma reticutosa. F. 2. Edwards. Tab. XXXII, fig. 4, a, 3. 
P. testé elongato-fusiformi, undique concentrice lineatd: spird acuminata: anfractibus 
convevis, ad humeros sub-angulatis et teniold depressa, obsolete curvo-plicata et sulco spirali 
angusto exarata, cinctis ; postice concavis, ad suturam marginatis ; ultimo anfractu in cana- 
lem latum brevem, antice reflexum, producto ; lineis concentricis supra margines et humeros 
anfractuum confertis, tenuibus; ceterum fortibus, sub-distantibus, irregularibus; omnino liners 
incrementi asperatis : apertura oblongo-oval ; labro arcuato, acuto, ad humerum sinuato; 
sinu latiusculo, profundo, sub-trigono. 
Shell elongated, fusiform, having the whole surface covered with spiral, raised 
lines ; spire pointed, produced, nearly equalling the aperture in length. The whorls, 
six or seven in number, are convex and bluntly angulated at the shoulders, which 
present a depressed, narrow, ribbon-like band, bearing a series of rather closely set, 
faint, crescent-shaped plications, formed by the successive rounded extremities of the 
sinus, and which are divided along the middle by a narrow but perspicuous furrow ; 
the posterior margins are slightly concave, and bordered round the sutural edge by a 
coarse, elevated line ; the last whorl is produced in front into a short, very wide, and 
slightly curved canal, the anterior extremity of which is bent a little backwards. The 
concentric lines are numerous and irregular, slender, and rather closely set over the 
margins and shoulders, but distant, thread-like, and much elevated over the middle 
and front parts of the whorls; and they are decussated by the perspicuous lines 
of growth, whence the surface has somewhat the appearance of being covered 
with fine network. The aperture is of a lengthened, oval form ; the outer lip arched, 
thin, sharp at the edge, and smooth within ; the sinus, which is placed at the shoulder, 
is rather wide, deep, and somewhat triangular in form, with a rounded extremity; 
and the columella is nearly straight, and presents a small crest in front. 
In the general character of the ornamentation this Pleurotoma resembles P. 
conifera ; but the lineation is of a rougher and more decided character ; the shell 
itself is wider, the spire relatively shorter, the whorls more convex, the anterior canal 
shorter and wider, and the sinus not so deep nor so narrow. ‘These differences strike 
the eye at once on comparing the two; and as the present shell occurs in a newer 
and distinct formation, I have retained it as a distinct species. 
From P. crenata (Nyst), with which it also presents a close analogy, it is separable 
by the wider and more concave margins, and the crenulated and tuberculated shoul- 
ders of the whorls in that species. 
Size—Axis, 1 inch and 1-]2th ; diameter, 5-12ths of an inch. 
Locality.—Barton, where it is rare. 
