334 GINGLYMACONCHA. PINNAD&. 
the old specimens have always a black epidermis, with decor- 
ticated umbones. 
5. Mopioua DISCORS. 
Shells oval, ventricose; their valves covered with a pale 
fuscous epidermis ; under the epidermis pinkish ; on each side 
longitudinally sulcated ; in the middle transversely striated. 
Length half an inch; height three-eighths of an inch. 
Mytilus discors, Linn. Syst. Nat. 1159. no. 261; Born. Mus. 
121; Vien. 5 Chem. Naturf. 10%) t..4.:f- 8g Came Vili. t. 
Ixxxvl. ft. 764-767 ;..Pult.. Cat: Dorset..38. 4.496 
Donov. Brit. Shells, t. xxv.; Mont. Test. Brit. 169; M. 
& R. Trans. Linn. Soc. vii. tl; ; Flem.Edinb. Encycl. vii. 
99; Dill. Dese. Cat. 319; Turt. Conch. Dict. 112. 
Modiola discors, Lam. Hist. Nat. des Anim. sans Vert. vi. 
part. 1. 114. 
Genus 65. Myti.us. 
Shells longitudinal, equivalve, arched above and somewhat 
winged, anteriorly gradually compressed, rounded, attenuated ; 
the umbones acute, nearly straight, termimal ; the hinge lateral, 
often toothless; the cardinal hgament marginal, slightly in- 
ternal; the muscular impression elongated, clubbed, and situ-— 
ated laterally. 
The tracheal tubes equal; the foot conic, short, longitudi- 
nally impressed ; the byssus generally affixed. 
1. MytTILus EDULIS. 
Shells oblong, anteriorly curved, compressedly-angulated ; 
posteriorly retuse ; towards their inferior margin incurvated ; 
the teeth nearly in a quadruple series; the umbones divarica- 
ting. Length three inches; height two and a half inches. 
Mytilus edule, Rond. Aquat. u. 46; didrov. Exsang. 512 ; 
Lister, Anim. Angl. t. iv. £. 28; Conch. t. ccclxii. f. 200; 
Merg. in Act. Paris.1711.t. ui. f. 4, 5; Linn. Faun. Suec. 
2156; Syst. Nat. xu. 1157; Penn. Brit. Zool. iv. 110. t. 
Ix. f. 72; Gmel. Syst. Nat. 3353; Brug. Encycl. Méth. 
