MoDioLA. MOLLUSCA. MYTILID^. 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. Ixxii. f. 2.) Turt. Biv- Brit. 200.— West 

 coast of England. 

 " Shell about two inches long, and one and a half broad ; very [flat 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, MIont. Test. Brit. 167. and Sup. G5. t. xxvi. f. 4 



Modiola discrepans. Turf. 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. Mmt. Test. Brit. 167 Modiola 



discors, Turt. Biv. Brit. 201. t. xv. f. 4, 5 — Adhering to Ascidice 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, naiTowing towards the posterior 

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

 Londmi Clay. — The large middleiigure is probably a distinct species belono-- 

 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. feyjs. — Subtriangular, 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 Avith transverse furrows. — Sower. Min. Cunch. t. ix. ujiper right hand 

 figure. — Lias. 



5. INI. 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, mitldle, and lower, figures London Clay. 



G. M. s?<i;ca»'jwato.— Oblong, smooth, gibbose; anterior side keel-formed, 

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

 t. ccx. f. 1. — London Clay. 



