Modiola. MOLLUSCA. MYTILIDiE. 413 



420. M. Gibbsii. — Shell somewhat triangular, striated trans- 

 versely, clothed with foliations, which are serrated on one edge. 

 {Leach. Zool. Misc. ii. 34. t. lxxii. f. 2.) Turt. Biv. Brit. 200.— West 

 coast of England. 



" Shell about two inches long, and one and a half broad ; veryjflat and an- 

 gular at the anterior side, regularly striated transversely, white and opake un- 

 der the skin, covered, more or less, with long foliations, which are constant- 

 ly notched down one of the sides." 



' - 421. M. discrepans. — Shell interruptedly longitudinally 

 striated, beaks obsolete, cuticle black. / 



Mytilus discrepans, Mont. Test. Brit. 167. and Sup. 65. t. xxvi. f. 4 



Modiola discrepans, Turt. Biv. Brit. 202. Linn. Trans Gregarious 



in deep water. At Newhaven it is called Corduroy Mussel. 

 Sometimes reaching to two inches in length ; compressed and rounded at 

 both extremities ; surface of the shell divided into three compartments by a 

 longitudinally striated space from the beaks along the back to the posterior 

 extremity, a smooth space from the beaks to the middle of the ventral mar- 

 gin, and another striated space, occupying a short space at the anterior extre- 

 mity. There are distinct transverse wrinkles. 



422. M. discors. — Shell interruptedly longitudinally striated, 

 beaks tumid, cuticle green. 



Mytilus discors, Linn. Syst. i. 1159. Mont. Test. Brit. 167.— Modiola 

 discors, Turt. Biv. Brit. 201. t. xv. f. 4, 5. — Adhering to Ascidiae and 

 the roots of Fuci. 



Shell seldom exceeding half an inch in length ; resembling the last in its 

 markings, but in form more tumid, broader, and the anterior side shorter. 



EXTINCT SPECIES. 



1. M. depressa.— Much depressed, ovate, narrowing towards the posterior 

 side ; surface smooth. — Sower. Min. Conch, t. viii. the three upper figures.— 

 London Clay. — The large middle figure is probably a distinct species belong- 

 ing to the Lias. 



2. M. pallida. — Oblong, gibbous, smooth ; inferior margin straight, poste- 

 rior side slightly swelled, beaks obtuse. — Sower. Min. Conch, t. viii. three 

 right hand lower figures. — In Green Sand, 



3. M. Icevis.— Sub triangular, very smooth, convex; inferior and posterior 

 margins nearly straight, united by a short curve, beaks small. — Sower. Min. 

 Conch, t. viii. left hand lower figure. — Lias. 



4. M. parallela. — Shell transverse, anterior and posterior sides parallel, co- 

 vered with transverse furrows. — Sower. Min. Conch, t. ix. upper right hand 

 figure. — Lias. 



5. M. elegans. — Oblong, gibbous, inferior margin straight, dentated ; ante- 

 rior side covered with transverse furrows ; posterior side swelling, smooth, 

 with a few transverse furrows near the base. — Sower. Min. Conch, t. ix. left 

 hand upper, middle, and lower, figures — London Clay. 



G. M. subcarinata.— Oblong, smooth, gibbose ; anterior side keel-formed, 

 rather obtuse; posterior lobe convex; front concave — Sower. Min. Conch. 

 t. ccx. f. 1. — London Clay. 



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