354 MOLLUSCA. MURICTDiE. Pleurotoma. 



25. F. peruvianus. — Subfusiform, ventricose, smooth, with fifteen thin cos- 

 tse ; 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- 



tiise carinae, crossed by thick ribs; beak half cylindrical, ribbed Sower. 



Min. Conch, t. ccccxxv. f. 1 — In Cray, 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 — Smcer. Min. Conch, t. ccccxxv. 

 f 2.— In Crag. 



Gen. LXXX. PLEUROTOMA. — 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, 



Do^i. Brit. Shells, t. clxix. f. 2.— In deep water, not common. 

 Length an inch, breadth a quarter ; yellowish-white, with light coloured 

 and brown bands ; whorls tapering, little rounded, with numerous obtuse 

 longitudinal ribs, crossed by well defined spii'al striae ; aperture ovate, the 

 outer-lip slightly crenulated by the spiral striae ; canal ratlier open, but pro- 

 duced in consequence of the bending in of the outer-lip, giving to the base 

 an acuminated aspect. 



350. P. shiuosa. — Whorls six, longitudinal ribs slightly 

 interrupted by a depressed space at the separating line. 



Murex sin. Mont. Test. Brit. 264. t. ix. f. 8 — In deep water, rare. 

 Length |ths of an inch, breadth a quarter, white, strong ; whorls slightly 

 comj)ressed, 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 ; t he 

 base has a blunt aspect. In a specimen which I found in Zetland, the spiral 

 striae are strong, giving the shell a coarsely reticulated appearance. 



EXTINCT SPECIES. 



1. V.atlenuata Fusiform, base attenuated ; longitudinally undulated; un- 

 dulations five or six, with a large compressed tubercle at the upper end oi 

 each ; volutions transversely striated ; aperture narrow, straight — Sotcer. 

 Min. Conch, t. cxlvi. f. 1 — London Clay. 



2. P. exorta. — Turrited, base conical, elongated ; whorls concave and 

 smooth above, below, longitudinally undulated and convex, with many ele- 

 vated subtuberculate dlines ; aperture ovate, elongated, canaliculated.)--Mu- 

 rex exortus, Brander, f. 32.— (S'oztrr. Min. Conch, t. cxvi, f. 2.) — London Clay. 



3. P. ro5<ra/a.~-Fusifbrm, with many transverse ridges and short costae, 

 volutions obscurely decussated, expanded, and slightly concave above, rather 

 ventricose and roughish below : aperture elongated, canalieulated — (Afurex 

 ros. Brander, f. 34.) — Smvcr. Min. Conch, t. clxvi. f. 3 — LoTidon Clay. 



