412 MOLLUSCA. MYTILID^. Modiola. 



EXTINCT SPECIES. 



1. M. ffl»ip?Ms.— Depressed, triangular, acutely angled at the base ; longi- 

 tudinally striated, excepting over the posterior side ; thin— Sower. Min. Conch. 

 t. vii. — In Oolite, 



2. M. an%MorM»i.— 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. pectijtatus Quadrangular, oblong, gibbose, longitudinally striated ; 



slightly curved ; beaks produced ; front straight.— 5'ow^en Min. Conch, t. 

 cclxxxii.— f/jpper Oolite. 



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 G^-een Sarid. 



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. sublcBvis.. — Oblong, triangular, rather curved ; disk obscurely keel- 

 shaped ; front straightish ; beaks acute ; lines of gi'owth rather prominent. 

 Sower. Mir. 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) — Sower. 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. 



1 0. M. crassus. — Shell very thick, ventral edge nearly straight, beaks 

 pointed. Flem. Edin. Phil. Journ. No. 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. ailvii. f. 5. Mytilus modiolus, Linn. Syst. i. 1158. Mont. 

 Test. Brit. 105.— On hard ground beyond low water-mai'k. 

 Length 5 or G 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 harbatus of Montagu. In some 

 cases, it is distorted by the byssus, and is then the IVI. iimlilicatiis of Pennant. 

 —This sj)ecies is eagerly sought after, as a bait for cod. 



