History of British animals - University of Guam Marine Laboratory

354 MOLLUSCA. MURICIDiE. Pleurotoma.25. F. pernvianus.— Subfusiform, ventricose, smooth, with fifteen thin costse; beak a little recurved.— Murex per. Sower. Min. Conch, t. ccccxxxiv.f. 1.— In Crag.26. F. alveolatus— Turrited; volutions ornamented with two spiral obtusecarinae, 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 ridges,with short spines at the points of their intersection ; whorls ventricose ;aperture oblong, produced into a short beak.— Sotver. Min. Conch, t. ccccxxv.f. 2.—In Crag.Gen. LXXX. PLEUROTOMA. — Shell turrited, canalstraight ;a gutter or notch at the junction of the outer-lipwith the body-whorl.— 349. P. gracilis.— Whorls ten ; ribs interruptedat the separatingline by a depressed spirally striated space; canal produced.Murex gracilis, Mont. Test. Brit. 267- t. xv. £ 5—M. emarginatus,clxix. f. 2 Don. Brit. Shells, t. In deep water, not common.Length an inch, breadth a quarter ; yellowish-white, with light colouredand brown bands ;whorls tapering, little rounded, with numerous obtuselongitudinal ribs, crossed by well defined spiral striae ; aperture ovate, theouter-lip slightly crenulated by the spiral striae ; canal rather open, but producedin consequence of the bending in of the outer-lip, giving to the basean acuminated aspect.350. P. sinuosa. — Whorls six, longitudinal ribs slightlyinterrupted by a depressed space at the separating line.Murex sin. Mont. Test. Brit. 264. t. ix. f. 8— In deep water, rare.Length f ths of an inch, breadth a quarter, white, strong;whorls slightlycompressed, and a little flattened at the top of each ; ribs numerous, elevated,bent at the angle of the flattened space, and diminishing towards theseparating line : regularly striated spirally ; aperture oblong, oval ; canalopen very short, in consequence of the outer-lip continuing entire ; ; thebase has a blunt aspect. In a specimen which I found in Zetland, the spiralstrise are strong, giving the shell a coarsely reticulated appearance.EXTINCT SPECIES.1. P. attenuata Fusiform, base attenuated ; longitudinally undulated; undulationsfive or six, with a large compressed tubercle at the upper end oieach ;volutions transversely striated ; aperture narrow1, straight—Sower.Min. Conch, t. cxlvi. f. 1—London Clay.2. P. exorta.—. Turrited, base conical, elongated; whorls concave andsmooth above, below, longitudinally undulated and convex, with many elevatedsubtuberculate dlines ; aperture ovate, elongated, canaliculated.)—Murexexortus, Brander, f. 32.— (Sower. Min. Conch, t. cxvi, f. 2.)—London Clay.3. P. rostrata Fusiform, with many transverse ridges and short costse,volutions obscurely decussated, expanded, and slightly concave above, ratherventricose and roughishbelow —:aperture elongated, canaliculated. (Murexros. Brander, f. 34.)—Sower. Min. Conch, t. clxvi, f. 3—London Clay.