354 
MOLLUSCA. MURICIDiE. Pleueotoma. 
25. F. peruviarms. — Subfusiform, ventricose, smooth, with fifteen thin cos- 
tae ; beak a little recurved — Murex per. Sower. Min. Conch, t. ccccxxxiv. 
f. 1. — In Crag. 
26. F. alveolatus. — Turrited; volutions ornamented with two spiral ob- 
tuse carinse, crossed by thick ribs; beak half cylindrical, ribbed — Sower. 
Min. Conch, t. ccccxxv. f. 1 — In Crag., Suffolk. 
27. F. cancellatus. — Lanceolate, acute, covered with acute decussating rid- 
ges, with short spines at the points of their intersection ; whorls ventricose ; 
aperture oblong, produced into a short beak — Sower. Min. Conch, t. ccccxxv. 
f. 2. — In Crag. 
Gen. LXXX. PLEUIiOTOMA. — Shell turrited, canal 
straight ; a gutter or notch at the junction of the outer-lip 
with the body-whorl. 
349 . P. gracilis. — Whorls ten ; ribs interrupted at the sepa- 
rating line by a depressed spirally striated space ; canal pro- 
duced. 
Murex gracilis, Mont. Test. Brit. 2G7. t. xv. f. 5 — M. emarginatus, 
Don. Brit. Shells, t. clxix. f. 2 — In deep water, not common. 
Length an inch, breadth a quarter ; yellowish-white, Avith light coloured 
and brown bands ; whorls tapering, little rounded, with numerous obtuse 
longitudinal ribs, crossed by well defined spiral strise ; aperture ovate, the 
outer-lip slightly crenulated by the spiral striae ; canal rather open, but pro- 
duceti in consequence of the bending in of the outer-lip, giving to the base 
an acuminated aspect. 
350. P. sinuosa. — Whorls six, longitudinal ribs slightly 
interrupted by a depressed space at the separating line. 
Murex sin. Mmt. Test. Brit. 264. t. ix. f. 8 — In deep water, rare. 
Length fths of an inch, breadth a quarter, white, strong; whorls slightly 
compressed, and a little flattened at the top of each ; ribs numerous, ele- 
vated, bent at the angle of the flattened space, and diminishing towards the 
separating line: regularly striated spirally; aperture oblong, oval; canal 
open ; very short, in consequence of the outer-lip continuing entire ; the 
base has a blunt aspect. In a specimen which I found in Zetland, the spiral 
stride are strong, giving the shell a coarsely reticulated appearance. 
EXTINCT SPECIES. 
1. P. attenuata Fusiform, base attenuated ; longitudinally undulated; un- 
dulations five or six, with a large compressed tubercle at the upper end 01 
each ; volutions transversely striated ; aperture narroAV, straight — Sower. 
Min. Conch, t. cxlvi. f. 1 — London Clay. 
2. P. exorta Turrited, base conical, elongated; whorls concave and 
smooth above, beloAv, longitudinally undulated and convex, with many ele- 
vated subtuberculate dlines ; aperture ovate, elongated, canaliculated.) — Mu- 
rex exortus, Brander^ f. ^2.— {Sower. Min. Conch, t. cxvi, f. 2.)— London Clay. 
3. P. rostrata ^Fusiform, with many transverse ridges and short costae, 
volutions obscurely decussated, expanded, and slightly concave above, rather 
ventricose and roughish below : aperture elongated, canaliculated.— (Murex 
ros. Brander., f. 34.)-^Sower. Min. Conch, t. clxvi. f. 3 — London Clay. 
