im MOLLUSCA. SOLENID^E. Panop.ea- 



Chamse-pholas angusta, List. Conch, t. ccccxxvi. — Solen minutus, Linn- 

 Syst. 1115 — Mya arctica, Fab. Fauna Groen. 407. — Curious Muskle. 

 Cordiner's Ruins, Plate No. 24. f. A. — Solen minutus, Mont. Test. Brit. 

 53. t. i. f. 4. — Hiatella minuta, and H. oblonga, Turt. Biv. Brit. 24. t. ii. 

 f. 12, 13 — Anatina arctica, ib. 49. t. iv. f. 7, 8. — Roots of fuci. 



This species, when young, has the spinous ridges very distinct ; and, when 

 not imbedded in stone, it adheres by a byssus. When old, the spinous ridges 

 disappear, and then in size, and other circumstances, it so exactly resembles 

 the preceding, as to leave little room for suspecting a specific difference. The 

 Mytilus prcecisus of Montagu, (Test. Brit. 165. t. iv. f. 2.) seems to be a varie- 

 ty in which the anterior end is truncated, and very short, and the beaks ele- 

 vated ; while the M. plicatus of the same author only differs in the beaks be- 

 ing small and slightly incurvated. 



EXTINCT SPECIES. 



1. H. sulcata.— Beak nearly terminal; both extremities rounded; shell 

 thin, concentrically sulcated, the ridges large retrally, formed by the union 

 of two or more ribs ; closely and obsoletely striated longitudinally, the 



striae consisting of minute tubercles Not uncommon in the Carboniferous 



Limestone of the Forth Coal-Field. 



Gen. CXXXVIII. PANOPtEA.— Shell transverse, unequal- 

 ly open at the sides ; a single conic tooth in each valve, with 

 an adjoining short compressed callus, to which an external 

 ligament is attached. 



575. P. Aldrovandi. — Truncated at both extremities, and 



coarsely wrinkled transversely. 



Chama Glycimeris, List. Conch, t. ccccxiv. — Mya Glycimeris, Dan. Brit. 

 Shells, t. cxlii — P. Gly. Turt. Biv. Brit. 42.— English coast, rare. 



Length about 4 inches, breadth 8 ; coarse and thick ; a series of wrinkles 

 behind the teeth. One specimen from the Dogger-bank occurred to Mr Do- 

 novan, and a fragment of a valve found on the beach at Teignmouth, by Dr 

 Turton, are the only British examples of this shell, which is sometimes found 

 on the coast of France and Spain. 



myam:. 



Gen. CXXXIX. MYA. — Equivalve, transverse, gaping; 

 hinge with a single projecting dilated tooth in the right 

 valve, for supporting the ligament, with a pit in the left. 



576. M. truncata. — Shell rounded anteally, abruptly trun- 

 cated retrally ; the ventral margin nearly straight. 



Concha hevis, List. An. Ang. 191. — Conch, t. ccccxxviii. — M. trun. Linn. 

 Syst. Nat. i. 1112. Penn. Brit. Zool. iv. 78. t. xli. f. 14. Mont. Test. 



Brit. 32. Turt. Biv. Brit. 31 Common near low water-mark, lodged 



in sand or gravel. 



