202 MYTILIDJ:. 



C. NIGRA, Gray. 



Elongated, rather compressed, not distinctly lobated, most 

 closely radiated (except in the middle) with raised and crenu- 

 lated striae ; epidermis brown in the adult, greenish in the young, 



Plate XLIV. fig. 5, and (Animal) Plate Q, fig. 7. 



Mytilus discors, var. Chemn. Conch. Cab. vol. viii. p. 195, pi. 86, f, 767. 

 „ „ ScHRoTER, Einleit. Conch, vol. iii. pi. 9, f. 15. 



„ „ var. Suecicus, 0. Fabr. K. Dankse Videnskah. Selskab. (Nj'e 



Samm.) 1788, p. 460 (in part). 

 „ discrei^ans, Mont. Test. Brit. Suppl. p. 65, pi. 26, f. 4. — Leach, Zoolog, 

 Miscellany, vol. ii. p. 36. — Index Testaceolog. pi. 12, f. 38. 

 I\[odiola 7iigra, Gray, Appendix to Parry's Voyage to North Pole. — Brit. Ma- 

 rine Conch, p. 249, f. 5. — Alder, Cat. Moll. Northumb. and 

 Durh. p. 81. — Hanl. Recent Shells, vol. i. p. 242, pi. 12, 

 f. 38. 

 „ discrepans, Fleming, Brit. Anim. p. 413. — Macgilliv. MoU. Aberd. 

 p. 238. — Brown, 111. Conch. G. B. p. 78, pi. 27, f. 8.— 

 SowERBY, Genera Shells , Modiola, f. 3. — Reeve, Conch. 

 Systemat. pi. 100, f. 3. — Philippi, Zeitschr. Malacol. 

 1844, p. 102. 

 „ coin2'>ressa, Menke, Cat. Conch. Malsburg (from Chemnitz's fig.). 

 „ depressa, Hanl. Recent Shells, vol. i. p. 242, note. 

 Crenella nigra. King, Ann. Nat. Hist. vol. xviii. p. 239. 



Although this rare shell was delineated in Montagu's 

 Supplement to the " Testacea Britanuica," as a large ex- 

 ample of his discrepans, the specific differences are of an 

 easily appreciable character : the most readily perceptible 

 are the nature of its striae, and the absence of any 

 marked lobation. Its shape is more or less oblong, and 

 slightly arcuated ; dilating chiefly just behind the middle, 

 and again attenuating posteriorly, it becomes decidedly nar- 

 row at the front extremity, which latter projects rather 

 more than in our discors, as the acute and tolerably promi- 

 nent beaks are not quite terminal. None of the British 

 examples we have seen are otherwise than fragile and 



