. Appendix to the Manual of Mollusca of Woodward, : containing such recent and fossil shells as are not mentioned in the second edition of that work . are numerous in the Carboniferoussystem, and range to the Middle Lias. In the typical Pleurotomaria the slit is large, and the bandis never concealed by the whorls of the spire. Schismope, Jeffreys, 1856. Etymology, schisme, a slit, and ope, a hole. Synonym, Woodwardia, Fischer, 1861. Type, S. striatula, Ph. Mediterranean. Shell like Scissurella, but the spire is laterally compressed, asin Stomatia, and is not so trochiform. The slit
. Appendix to the Manual of Mollusca of Woodward, : containing such recent and fossil shells as are not mentioned in the second edition of that work . are numerous in the Carboniferoussystem, and range to the Middle Lias. In the typical Pleurotomaria the slit is large, and the bandis never concealed by the whorls of the spire. Schismope, Jeffreys, 1856. Etymology, schisme, a slit, and ope, a hole. Synonym, Woodwardia, Fischer, 1861. Type, S. striatula, Ph. Mediterranean. Shell like Scissurella, but the spire is laterally compressed, asin Stomatia, and is not so trochiform. The slit in the peristomeof the young shell is converted into a foramen in the adult; itdoes not commence until the animal is half grown. S. striatula is a littoral species, whilst all the species of Scis-surella inhabit deep water. Fossil, 1 species, Miocene, Bordeaux. Distribution, 4 species. Mediterranean, Japan. Scissurella and Schismope are the analogues respectively toPleurotomaria and Trochotoma, differing only in size; but in thetwo former genera the shell is translucent, not nacreous, as inthe two latter. Ditkemaeia* (pars, DOrb.), T. Deslongchamps, Fig. 15. Ditremariu , Central tooth, b, Callosity of the base, c, Tooth on the right, d, Tooth on the left. Type, D. quinquecincta, Ziet. sp. Coral Eag. Natheim, &c. Shell trochiform; in place of the respiratory slit of Trocho-toma, there are two elongated oval holes united by a transversefissure; the base of the shell presents a large callosity, theumbilicus is deeply excavated, and a rounded tubercle arises * See p. GASTEROPODA. from it; the aperture is contracted, and the upper angle ofeach lip bears a more or less distinct tooth. Distribution, 2 species, Great Oolite and Coral Rag, Franceand Germany. Sub-family—Bellerophontin^:. Genera :—Porcellla (p. 344), Bellerophon (p. 344) (withBucania), and Tremajtotus, Hall, 1863. Type, Bucania Chicagoensis, MChesney. Shell thick, aperture dilated; having
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