PROSOBRANCHIATA. 273 
This Pleurotoma, which is remarkable for the smooth surface and the short, 
cup-like form of the whorls, appears to be quite distinct; it presents a close 
resemblance to P. regularis (Van Bened.); but it is narrower, with a more pointed 
spire ; and the whorls are shorter, wider, and with more depressed margins. 
Size-—The extremity of the anterior canal is broken off; the axis of the perfect 
shell would be nearly 3 inches and 1-4th; diameter, 9-12ths of an inch. 
Locality.—Shinfield. 
Section I (Shells fusiform) continued. 
B.—Sinus on the shoulder of the whorl. 
a. Canal elongated. 
No. 197. Pxreurotoma aspera. F. &. Edwards. Tab. XXIX, fig. 14, a, 6. 
P. testa elongata, fusiformi, sub-turritd, lineis elevatis longitudinalibus spiralibusque 
sese decussantibus undique asperald: spird elevatd: anfractibus antice planulatis, ad 
humeros obtuse carinatis, postice cavatis, marginatis ; ultimo anfractu in canalem longum 
contortum, recurvum, producto; carind tenioleformi, denticulatd: lineis longitudinalibus 
acutlis undatis ; lineis spiralibus pre-eminentibus, denticulatis; apertura oblongo-ovatd ; 
labro leviter arcuato, acuto, intis plicato ; sinu oblongo, profundo, ad humerum collocato. 
Shell oblong, fusiform, with a turreted, pointed spire, rather elevated, nearly 
equalling the aperture in length; the whole surface ornamented with numerous 
sharp, undulating, longitudinal, raised lines, decussated by concentric, raised lines, 
more prominent than the longitudinal lines, and denticulated at the points of 
decussation, imparting a rough character to the shell. The whorls are flat-sided, 
girt round the shoulders by a narrow, slightly raised, ribbon-like band, which gives to 
them the appearance of being obtusely keeled; and the posterior margins are concave, 
slightly thickened at the edge, and bordered by a sharp, elevated line, which runs 
round the suture; the band on the shoulders presents a series of narrow, vertical 
tubercles, corresponding with the longitudinal lines. The aperture is of an oblong- 
ovate form, and terminates in front in a long, narrowish, slightly curved canal, 
bent backwards at the anterior extremity ; the outer lip is a little arched, thin, and 
sharp on the edge, thickened and strongly plicated within; and the sinus, which 
is placed on the shoulder, is oblong and very deep, with nearly parallel margins. 
Occasionally specimens occur in which the posterior margins of the whorls, 
between the sutural ridge and the shoulders, are smooth ; others, in which the margins 
, 35 
