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Observations on the Genus Ocythoe of Rafinesque, with a Description 

 of a new Species. By William Elford Leach, M.D. F.R.S. Read 

 June 5, 1817. [Phil. Trans. 1817,;?. 293.] 



Several ancient and modern writers have described a species of 

 Ocythoe often found in the Paper Nautilus, and have considered it as 

 belonging to that shell. Sir Joseph Banks and other naturalists 

 have maintained a contrary opinion, and have considered the Ocythoe 

 as a parasitical inhabitant of the Argonaut's shell. Rafinesque, whose 

 opportunities for observation were commensurate with his talent in 

 observing, regarded it as a peculiar genus, allied to the Sepia octo- 

 podia of Linnaeus, and as a parasitical resident of the above-mentioned 

 shell. 



The observations of the late Mr. John Cranch, zoologist to the 

 Congo expedition, have, in the opinion of Dr. Leach, removed all 

 doubt upon this subject. In the Gulf of Guinea he took several 

 specimens of a new species of Ocythoe in a small Argonauta, and 

 placed two of them in a vessel of sea- water, so as to observe their 

 motions. When adhering to the basin the shell could be removed ; 

 they had the power both of retiring within it and of entirely quitting 

 it. One having left the shell lived several hours, and showed no de- 

 sire to return. Others quitted the shell while taking up the net. 

 Ocythoe differs from the Polypus in the shortness of its arms; in 

 having pedunculated instead of simple suckers ; in having four ob- 

 long spots on the inside of the tube, and a small fleshy short tubercle 

 immediately above the bronchise, on each side, a character common 

 to this genus, to Loligo, and to Sepia, but which does not exist in 

 Polypus. 



This paper concludes with a descriptive reference to the drawing, 

 which shows the animal in and out of the shell. It is called by the 

 author Ocythoe Cranchii. 



The distinguishing Characters between the Ova of the Sepia, and those of 

 the Vermes Testacea, that live in Water, explained. By Sir Everard 

 Home, Bart. V.P.R.S. Read June 5, 1817- [Phil. Trans. 1817, 

 p. 297.] 



After alluding to the erroneous notions of Linnaeus and other natu- 

 ralists, concerning the animal that forms the shell called Argonauta, 

 and to his own opinion that it is an internal shell, the author pro- 

 ceeds to show that this shell is not the produce of the species of 

 Sepia often found in it, for the ova of this Sepia are not those of an 

 animal of the Order Vermes Testacea. The blood of oviparous ani- 

 mals, while in the egg, is aerated through its coats ; but in the 

 Vermes Testacea, if the shell were formed in the egg, the process of 

 aeration would be impeded; so that the animal's shell is formed after 

 it has left the egg. Animals that live in water require some defence 

 while the shell is forming ; they are therefore inclosed in a camerated 

 nidus. That of the Helix ianthina, taken in the voyage to the Congo, 



