MYTILUS. 319 



discrepans. 40. Shell transversely ovate, com- 

 pressed, with the two sides longitudinally 

 ribbed, and plain in the middle. 



Mytilus discrepans. Montagu Test. p. 169, and Supp. p. 



65. t. 26. f. 4. 

 Mytilus discors, Var. Chemnitz, viii. p. 194. t. 86. f. 766 



and 767. Schroeter Einl iii. p. 446. t. 9- f. 15. 

 Modiola discrepans. Leach Zool. Misc. ii. p. 36. 

 Anodonta. Enc. Meth. p. 204. f. 4. 



Inhabits the Baltic. Chemnitz. Coasts of Great Britain. Mon- 

 tagu. 



Shell sometimes fourteen lines long, and two inches broad, but 

 is generally much smaller ; it is nearly allied to M. discors, 

 and Mr. Montagu says, " The principal distinctions are that 

 this is very little convex, whereas the other is nearly as thick 

 as it is broad ; this is rounded and broadest at the anterior 

 side ; the other is smallest on that side, and runs out to an 

 obtuse point ; it has only eight or nine clearly defined ribs on 

 the side next to the beak, whereas the other has double that 

 number, which character is invariable ; and this is never 

 otherwise than of an uniform colour without spots or markings 

 of any kind." 



discors. 41. Shell transversely sub-oval, very con- 

 vex, with the two sides longitudinally ribbed 

 and plain in the middle. 



Mytilus discors. Linnaus Syst. Nat. p. 11 59. Da Costa 

 Brit. Conch, p. 221. t. 17- f. 1. Chemnitz, viii. p. 191. 

 t. 86. f. 764 and 765. Schroeter Einl. iii. p. 444. Gme- 

 lin, p. 3356. Donovan, i. t. 25. Montagu Test. p. 

 167. Maton and Racket, in Lin. Trans, viii. p. 111. 

 t. 3. f. 8. Dorset Cat. p. 40. t. 2. f. 1. 

 Inhabits the coasts of Norway and Iceland. Linnaw. Great 



Britain. Da Costa, fyc. Greenland. Fabricius. 

 Shell about three-eighths of an inch long, and half an inch 

 broad ; of a pale greenish or reddish white colour, covered 

 with a glossy olive epidermis ; each valve is divided into three 

 compartments, of which those on the sides are longitudinally 

 ribbed, and the middle is smooth, or only very faintly wrin- 

 kled transversely. 



