History of British animals - University of Guam Marine Laboratory

374 MOLLUSCA. ACEPHALA. Spirifer.71. T. hemisphmrica.— Hemispherical, with a produced incurved beak, Iongitudinallystriated ; striae very numerous—Sower. Min. Conch, t. cccxxxvi.F. 1.—In Oolite.72. T. rigida.— Orbicular, plaited ; plaits granulated, increasingin numbertowards the margin lesser valve ;nearly flat, the other convex, with a smallbeak Sower. Min. Conch, t. dxxxvL f. 2.— In Chalk.73. T. striatula Imperfectly bilobate, compressed, longitudinally ovateand striated ; bfront truncated, sometimes with a sinus striae ; granulated, repeatedlyforked.— Mant. Geol. Suss. 131. t. xxv. f. 7, 8, and 12. Sower. Min.Conch, t. dxxxvL f. 3, 4, 5.—In Chalk.74. T. pisum Suborbicular, rather square, thick, depressed, plaited ; plaitsnumerous, simple, sometimes granulated front ; slightly elevated, beak small,incurved Sower. Min. Conch, t. Dxxxvi. f. G, 7—In Chalk Marl.75. T. rostrata.— Suborbicular, gibbose, plaited; plaits many, rounded;beak large, produced, slightly incurved, pointed ; front slightly elevated—Sower. Min. Conch, t. Dxxxvii. f. 1, 2.—In Chalk Marl.76. T. truncata.— Semicircular, plaited; plaits sharp, from 9 to 20, some ofthem forked ;front elevated with from 1 to 5 plaits ;hinge-line straight, equalto the width of the shell ;lesser valve nearly flat, the other subcorneal, witha straight beak, which is flat in the front—Soiver. Min. Conch, t. Dxxxvii.—In Green Sand.77. T. Gibbsiana Suborbicular, rather triangular, ventricose, with numerousrounded, simple plaits ; front much elevated, with about 10 or 12 plaits,flattened; beak small, incurved, pointed; small valve most convex—Soiver.Min. Conch, t. Dxxxvii. f. 4.— In Green Sand.78. Mantelliana.—Transversely obovate, gibbose, plaited; plaits 10, sharp,front elevated with 4 to 6 plaits ; beak prominent but small. — Sower. Min.Conch, t. Dxxxvii. f. 6—In Chalk Marl.Besides the above extended list of extinct species (of which not a few willprobably be found to be varieties), there are indications of a few other speciesin the writingsof British geologists;but too obscure to warrant their insertionhere.Gen. SPIRIFER. — Hinge transverse; perforationfor theligament triangular, in a longitudinal flattened space underthe beak ;two spirallycoiled linear appendages tothe hinge, nearly filling the shell.1. S. Giispidatus Apex of the perforated valve broadly truncated, forminga flat triangular space, the base of which is in the hinge, longitudinally ribbedwith a broad mesial furrow ; the other valve ribbed, with a mesial ridge—Anomia cusp. Mart. Linn. Trans, iv. 45. t. hi.— Spir. cusp. Sower. Min.Conch, t. exx and t. cccclxi. f. 2.— In Carboniferous Limestone.2. S. trigonalis.— Gibbose, transversely striated, with about twenty-six radiatingsulci ; hinge-line as long as the shell is wide ;front semicircular ;the three central ridges elevated ;beaks incurved, approximating.— Anomisestriata, Ure, Ruth. 314. t. xv. f. 1 An. trigonalis, Mart. Derb. t. xxxvi.Spir. trig. Sower. Min. — Conch, t. eclxv. In Carboniferous Limestone.f. 13. S. triangularis" Differs from S. trigonalis principallyin the sides beingdirect or simight, not rounded, forming acute angles with the hinge; and,