OCR Text |
Show 812 CJE.C1T3JE OF THE 'CHALLENGER' EXPEDITION. [Dec. 16. glass. At about one third from the apex they are replaced by irregularly disposed striations. Towards the mouth the shell is slightly dilated ; but just at the edge it is faintly constricted and then even more faintly reflected. The septum is minute and very slightly elevated in the form of a centrally mamillated button. The species differs from C. bipartitum (' Les Fonds de la Mer,' vol. i. p. 185, pi. xxv. figs. 9,10) from Mexico, in size, thinness of shell, form of mouth and septum, and in sculpture. From C. semicinctum (Les Meleaginicoles, p. 42; Les Fonds de la Mer, p. 8) it differs in size, thinness, arrangement and form of the rings, and in the form of its septum. 15. CECUM CRYSTALLINUM, n. sp. July, 1875. Reefs off Honolulu. 40 fms. One specimen. Length ? Breadth 0*3 mm. An imperfect specimen, the upper part being broken off. It is evidently a new species, though nearly related to C. striatum (Fonds de la Mer, vol. i. pp. 49, 170, pi. v. fig. 3), from which it differs in that the shell towards the mouth expands and is thereafter contracted so as to form a minute gorge, with a slightly reflected lip. At first sight it resembles C. glabriforme, Carp. (Brochina); but it is straighter, and the texture of the shell is different, exhibiting under the microscope fine longitudinal striations. Though unable, from its imperfect condition, to offer a full description, the specimen is so clearly a new species that I venture to attach to it the name I have given above. |