m 
MOLLUSCA. MYTILID^. 
Modiola. 
EXTINCT SPECIES. 
1 . M. awjoJws.— Depressed, triangular, acutely angled at the base ; longi- 
tudinally striated, excepting over the posterior side ; thm,-~Sowei\ Min. Conch, 
t. vii— In Oolite. 
2. M. Elongated, ovate, rather gibbose, smooth, straight; 
beaks obtuse, nearly close ; hinge toothed. — Sower. Min. Conch, t. cclxxv. 
1, 2, 3. — In Crag. 
3. M. alaformis. — Obovate, with an acuminated beak, curved, depressed, 
smooth, with teeth in the hinge. Sower. Min. Conch, t. cclxxv. f. 4.— In 
Crag. 
4. M. peetinatus. — Quadrangular, oblong, gibbose, longitudinally striated ; 
slightly curved ; beaks produced ; front straight. — Sower. Min. Conch, t. 
cclxxxii.—. t/pper Ooliie. 
5. M. edentulus. — Elongated, smooth ; disk obscurely keel-shaped ; beak 
sharp ; posterior side nearly straight ; no tooth in the hinge. — Sower. Min. 
Conch, t, ccccxxxix. f. 1. — In Green Sand. 
6. M. lanceolatus . — Lanceolate, slightly curved, smooth; disk keel-formed;, 
posterior side flat ; beaks acute. — Sower. Min. Conch, t. ccccxxxix. f. 2 In 
Green Sand. 
7. M. suhlcBvis. — Oblong, triangular, rather curved ; disk obscurely keel- 
shaped ; front straightish ; beaks acute ; lines of growth rather prominent. 
Sower. Min. Conch, t. ccccxxxix. f. 3. — Lower Oolite. 
8. M. Braardii. — Convex, straight, pear-shaped, elongated; beaks acute, 
terminal, (within each beak a plate is extended to the opposite edge for the 
support of a tendon, and within that is a flat angular process).— Min. 
Conch, t. Dxxxii. f. 2.— In Crag. 
9. M. affinis. — Obliquely oblong, carinated, smooth ; sides parallel, straight ; 
the posterior arched in the young shell ; hinge without teeth, its anterior 
margin reflected — Sower. Min. Conch, t. DXxxii. f. 1 — In Crag. 
10. M. crassus. — Shell very thick, ventral edge nearly straight, beaks 
pointed. Flem. Edin. Phil. J ourn. N o. XXIV. 246, tab. ix. f. 3. Gregarious. 
In limestone slate-clay and clay ironstone in the independent coal formation in 
Scotland. 
Gen. civ. MODIOLA. — Shell subtransverse, equivalve ; 
beaks nearly terminal, hinge without teeth, and the liga- 
ment external. 
419. M. vulgaris . — ^Shell smooth, or slightly wrinkled, com- 
pressed and prominent at the extremity of the ligament ; beaks 
tumid. 
List. Conch, t. Mlvii. f. 5. Mytilus modiolus, Linn. Syst. i. 1 158. Mont, 
Test. Brit. 165 — On hard ground beyond low water-mark. 
Length 5 or 6 inches, breadth about one-half less ; rounded at both extre- 
mities ; cuticle thick, yellowish-brown, sometimes with simple leaf-like fila- 
ments. In this last state, it is the Mytilus harhatus of Montagu. In some 
cases, it is distorted by the byssus, and is then the M. umbilicatus of Pennant. 
—This species is eagerly sought after, as a bait for cod. 
