History of British animals - University of Guam Marine Laboratory

414 MOLLUSCA. MYTILIMJ. Lithodomus.7. M. biparlita.— Elongated, smooth, rather gibbose ; anterior side obtuse,suddenly raised above the posterior ; posterior lobe irregular Sower. Min.Conch, t. ccx. f. 3, 4—Iron Sand. Fig. 4. if from Carboniferous Limestonenear Cardiff, will yet rank as a distinct species.0. M cequalis.— Oblong, convex, smooth, anterior lobe large, obscurely defined—Sower.Min. Conch, t. ex. f. 2 Iron Sand.9. M. minima.— Ovato subtriangular, smooth ; front nearly straight, endsrounded, posterior lobe small, distinct—Sower. Min. Conch, t. ex. f, 5, G, 7.—Lias.10. M. cuneata— Elongated, convex, smooth ; anterior part cuneated ;back arched ; front slightly concave ; posterior side distinct, convex,— Sower.Min. Conch, t. ccii. f. 1.— Inferior Oolite.11. M. giblosa — Elongated, reniform, very gibbose, smooth; backarched.—broad,Sower. Min. Conch, t. ccii. f. 2. — Inferior Oolite.12. M. reniformis — Oblong, subreniform, smooth ; anterior lobe slightlyexpanded; posterior lobe small. — Sower. Min. Conch, ccxii. f.1, 2, 3 InfcriorOolite.13. M. imbricata— Oval, elongated; with imbricated ridges upon the surface; back angular, front concave—Sower. Min. Conch, t. ccxii. f. 1, 2, 3Inferior Oolite.14. M. Hillana— Depressed, elongato-ovate, concentrically striated ; posteriorend narrow ; front slightly concave ; posterior lobe obscure. — Sower.Min. Conch, t. ccxii. f. 2 Lias.15. M. aspera.— Ovate elongated, posteriorly pointed ; very gibbose, longitudinallystriated ; striae elevated, rough, very numerous ; posterior lobeobscure, wrinkled, small—Sower. Min. Conch, t. ccxii. f. 4 Inferior Oolite.] 6. M. plicala.— Transversely elongated, slightly curved ;back nearlystraight, plaited obliquely—List. Conch, t. Dxxi.' f. 7G. Sower. Min. Conch,t. ccxlviii. f. 1.— Inferior Oolite.17. M. scalprum.— Transversely elongated, slightly compressed, nearlysmooth ; posterior side small, undefined ; anterior side slightly curved andproduced—Sower. Min. Conch, t. ccxlviii. f. 2 In Lias.18. M. aliformis.—Triangular, inflated ; back straight ; posterior lobe verysmall ; anterior lobe flattish ; central part convex, elongated, with projectingbeaks—Sower. Min. Conch, t. ccii.— In Oolite.Gen. CV. LITHODOMUS.—Shell subcylindrical, roundedat both ends ; beaks nearly terminal ;no teeth ;ligamentalline nearly straight.423. L. lithophagus.— Cuticle green, finely striated by thelayers of growth inside ; glossy)iridescent.Mytilus lith. Linn. Syst. i. 1156. Sower. Linn. Trans, viii. 270. t.- vi.f. 1, 2, 3, 4, 5—In cavities of Limestone.The specimens inmy possession are about an inch in length, and fourtenthsbroad. At first, this species adheres by a byssus, which ceases togrow after a lodgment in the stone has been effected ; the calcareous matterof which frequently adheres to the surface of the shell like a crust, or becomesattached to the retral extremity in a beak -like process.