(520 COMMANDER KNOCKER ON PELAGIC SHELLS. [Nov. 26, 



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 favour- 

 able. 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 CleodorcB ; these seldom before the sun had set, and 

 usually 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 inter- 

 ruptions which continually occur on board ship, they will be of a 

 very superficial nature. 



Cleodora pyramidata (Peron). 



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 No- 

 vember 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 aj)peavs to differ entirely from 

 C. cuspidata. 



Cleodora, or Creseis? 



On l/th 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 subu-inhilicafa, trochoidea, nitida, violacea, oblique crebriJirafa, an- 

 fracfu uttiino convexo in medio valdc carinato ; apertura siibfrianyulari, 

 labro in media profunde sinuate. .. yours very sincerely, 



"ArtHVK Al>Ai£S." 



