162 WORMS. TESTACEA. 46. 41. 



Shell about 2 inches long, one and a half broad, generally much 

 distorted and irregular on the surface, with numerous unequal 

 fine ribs, rufous, whitish, or variegated; ears sometimes laree, 

 sometimes hardly visible. 



293. P.glaber. Ears equal: shell very thin, with 15 

 faint rays, within marked with rays divided by a 

 single groove. 



Pennant Br.Zool. iv./». 102. n. 68. 



291. P. varius. Ears very unequal : shell with about 12 

 ribs beset with transverse prickly scales. 



Br. Zool.t. 61. f. 64. Donov. tab. \.f.\. 



Shell about 2 inches wide, 2 and a quarter long, variously co- 

 loured and marked,.with rough spinous protuberances down the 

 rays especially towards the margin : ears very unequal, the larger- 

 one wrinkled and armed beneath with 5-7 spines, the smaller 

 with a double row of spines,. 



295. P. o'jsoietas. Ears unequal : shell dark purple, 

 with numerous fine longitudinal striae 8 or 10 of which 

 are more prominent. 



Br. Zool< t. 61. f. 66. Donovan, tab. \.f. 2. 



Shell hardly an inch long, dark purple with 8 obsolete darker 

 rays, smooth and brownish within, equivalve : ears unequal, the 

 larger-one wrinkled and striate. 



296. P. laovis. Ears unequal : shell flat thin, pellucid,, 

 smooth except a few faint concentric ridges. 



Montague Brit. Shells, p. 150. tab. 4./. 4. 



Shell nearly orbicular, about 6 lines long, yellowish-white,, 

 purplish-brown, or chesnut, often variegated, within white with 

 the margin crenulate, sometimes striate near the margin: ears 

 strongly striate longitudinally and very finely transversely. 



46 OSTREA. m Oy&ter. 



297. O.edulis. Suborbicular, rugged, with undulate, 

 imbricate scales ; one valve flat and entire . 



Da Costa tab. li.f. 6. Linn. Trans, vi.r. 18./. 9. 10. 



<S#e// varying much in size and bulk, generally brown, with une- 

 qual valves, the upper-one flat, the lower very convex and rugged 

 transversely striate and often longitudinally ribbed, within pearly 

 white: beak rather oblique, with a row of small knobs running 

 down each side. 



298. O. saxqtilis. Suborbicular, very thin, pellucid, a 

 little scaly : the larger-valve with strong longitu- 

 dinal ribs. 



Found adhering to rocks and . stones near the low water mark 

 at the Mumbles, and differs from the last in being always very 

 thin and transparent, not so rugged, and in the lower-valve 

 being furnished with strong longitudinal ribs which often end in 

 hollow scales : Shell 2 or 3 inches long, variously shaped, bufc 

 generally suborbicular, oblong, or subtriangular, mostly with a 

 fine purple tinge, within glofsy white. 



47. ANOMIA. 



299. A. Ephippium. Suborbicnlar, pellucid, with wrin- 

 kled undulate plaits, irregularly sinuate on the 

 margin. 



Br. Zool. t. 62. Donov. t. 26. Da Cost. t. 1 V.f. 3. 



Shell 2 or 3 inches wide, produced on one side, perlaceous Witb- 

 various tints of green purple violet or yellow, the perforated 

 valve transversely striate. 



