388 MOLLUSCA. BIVALVIA. Lima. 



Gen. XC V. LIMA. — Shell longitudinally oblong, with ears ; 

 beaks remote ; ligament external. 



385. L. fragilis. — Shell with irregular longitudinal rough 



ribs ; the ears oblique. 



Pecten frag. Mont. Test. Brit. Sup. 62 — L. bullata, Turt. Biv. Brit. 217- 

 t. xvii. r. 4, 5. — On different parts of the coast, rare. 



Length sometimes exceeding an inch and a half ; breadth an inch ; white ; 

 valves equal, little raised ; one side with the edge straight ; the other arcu- 

 ated ; ribs numerous, unequal, irregularly grouped, most prominent on the 

 middle of the shell, and rendered rough by the irregular lines of growth ; 

 margin nearly smooth ; beaks prominent. This shell (which may prove a 

 var. of Ostrea glaciulis of Poli, Test. 11. t. xxviii. f. 19, 20.) was observed by 

 Montagu on the coast of Devon, afterwards by Dr Turton, at Bray, in Ire- 

 land ; and more recently on the coast of Scotland, near Appin, by Captain 

 Carmichael. — A single valve, communicated by the last observer, is l T 6 „ths 

 of an inch in length. 



386. L. subauriculata. — Shell finely striated longitudinally, 



the ears nearly rectangular. 



Pecten sub. Mont. Test. Brit. Sup. 63. t. xxix. f. 2 — L. sub. Turt. Biv. 

 Brit. 218 — On different parts of the coast, from Devon to Zetland, 

 rare. 



Length fths ; breadth |th of an inch ; pellucid, nearly equilateral ; two 

 conspicuous mesial opake striae ; margin slightly crenulated. 



EXTINCT SPECIES. 



1. L. gibbosa Elongated, gibbose, smooth, longitudinally plicate in the 



middle ; ears undefined. — Sower. Min. Conch, t. clii. — Under Oolite. 



2. L. rudis. — Obovate, oblique, with seven longitudinal costae ; anterior 



ear open with thickened lobes Sower. Min. Conch, t. ccxiv. f. 1. — Middle 



Oolite. 



3. L. antiquata Elliptical, depressed, coarsely striated ; anterior ear 



deeply wrinkled, open Sower. Min. Conch, t. ccxiv. f. 2. — In Lias. 



4. L. proboscidea Broad, ovate, convex, with twelve ribs, each furnished 



with several large tubular processes ; ears small — Sower. Min. Conch, 

 t. cclxiv. — Inferior Oolite. 



Gen. PL AGIOSTOM A.— " An oblique eared bivalve ; hinge 

 destitute of teeth or internal pit ; line of the hinge straight 

 in one valve, in the other deeply cut by an angular sinus. 1 ' 

 — (Sowerby.) 



1. Y.giganteum Smooth, depressed, deltoid, with the posterior side round- 

 ed in to the front ; ears small, anterior one longest, placed in a lai-ge broad 

 and straight furrow ; beaks pointed ; surface obscurely marked with diver- 

 ging striae. — Sower. Min. Conch, t. lxvii — In Lias. 



2. P. spinosum Obovate, longitudinally furrowed ; sides nearly equal, 



