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Show 620 COMMANDER KNOCKER ON PELAGIC SHELLS. [N I may, perhaps, be allowed to remark that I found the tow-net but of little service during the daytime, the hours between sunset and sunrise, especially on moonlight nights, being the most favourable. I also remarked, generally, that the Atalantce were the first to come to the surface, the species of Creseis next, and lastly the Hyalece and Cleodoree; these seldom before the sun had set, and usuallv an hour after. In submitting this "chain" of Pelagic Mollusca to the Members of the Society, I trust they will make all allowances for imperfections in a first attempt. I will now proceed with a few observations on the several varieties ; but having no microscope on board, and with the number of interruptions which continually occur on board ship, they will be of a very superficial nature. CLEODORA PYRAMIDATA (P6ron). C. lanceolata (young), Rang. I believe these species to be different, as I found C. pyramidata and C. lanceolata equally large. In all cases the characters were distinct, and there were no intermediate forms, C. pyramidata being invariably more elongated and compressed, the line from the lateral to the terminal points being nearly straight, whereas in C. lanceolata the lateral points diverge much more, are more posterior, and the line from these to the terminal one is much more incurved. In a work on the natural history of California I found the name Cleodora exacuta mentioned as the species of that coast. But I cannot find any difference between it and C. lanceolata, and have included them both in the same column. CLEODORA (not named). I obtained only three specimens of this shell (18th and 21st November and 11th March), all rather damaged; the lateral points long, attenuated, sharp, and rather inclined forwards; terminal point short and much curved upwards. Shell glassy, very brittle, white, and strongly striated across from dorsal ridge to ventral edge. That obtained on the 11th March has the terminal point less curved, and the lateral ones directed more forwards. I do not find this species described in Rang's work. It appears to differ entirely from C. cuspidata. CLEODORA, or CRESEIS? On 17th March 1868. A large, long, smooth, glassy shell, rather the colour is of a uniform violet. The chief peculiarity, however, is its shining appearance. " IANTHINA NITIDA, A. Ad. ''I. testa subumbilicata, trochoidea, nitida, violacea, oblique crebrilirata, ultimo convexo in medio valde carinato; apertura subtriangulari, labro in medio profunde sinuato. „ Y o u r g yery sincerelyi "ARTHUR ADAMS." |