Modiola. MOLLUSCA. MYTILID.E. 
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, Mont Test. Brit. 167. and Sup. 65. t. xxvi. f. 4 
Modiola discrepans, Turt Biv. Brit. 202. Einn. 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 Ascidi[e and 
the roots of Euci. 
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. dcprma.— 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. /fern's.— 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 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, 
Avith a few transverse furrows near the base. — Sower. Min. Conch, t. ix. left 
hand upper, middle, and lower, figures. — London Clay. 
6. M. subcarinata.— Oblong, smooth, gibbose ; anterior side keel-formed, 
rather obtuse ; posterior lobe convex ; front concave — Min. Conch, 
t. ccx. f. 1. — London Clay. 
3 
