108 



Z. M. t. 72. /. 2. Somewhat triangular, very flat and 

 angular anteriorly, regularly striated transversely, 

 clothed with foliations which are serrated on one side, 

 white and opaque under the cuticle. 2...H. W. Coasts. 



M. DISCORS. Turt.B.p.201. t: 15. f. 4,5. F.p.413. 

 MYTILUS D. Lin. l\59.Mont.p. 167. M,Dis- 

 CREPANS. Lam. 15. Da. Cost. t. 17./. 1. Pen. 4. p. 

 167. Lin. T. 8. p. 111. t. 3./. 8. Dor. Cat. p. 40. 

 t. 2.f. l.D. p. 3\9.Turl. D. p. 1 12. Oval, very 

 tumid anteriorly rather pointed and somewhat contracted 

 at the ventral margin ; divided into compartments, the 

 central being nearly smooth, the extremes with longitu- 

 dinal ribs; cuticle green or brownish horn-color ; beaks 

 quite terminal, very obtuse and twisted into a single 

 flat volution. 0,44. W. Coasts and Ireland. 



M. DISCREPANS. Turt. B.p. 202. F. p. 413. 

 MYTILUS D. Mont. p. 119. and Sup. p. 65. t. 26. f. 

 4. Lin. T. S.p. 111. t. 3./. 9. Pen. 4. p. 241. 

 D.p. 319. Turt. D. p. 112. Oval, flattish, rounded 

 anteriorly, slightly ribbed longitudinally at both ends ; 

 beaks not quite terminal. . W. Coast and Ireland. 

 Like the last but flatter broader and rounder at the 

 end opposite the hinge, where the ribs are only eight in 

 number., the color too is blacker. 



