302 Zoological Society. 



On this account he speaks of the animal in question as the Jrg. Mans, 

 discarding the name of Ocytho'e Cranchii applied to it by Dr. Leach. 



In carefully describing the specimen before him, Mr. Owen coi- 

 rects some errors in the account given of the animal by its original 

 describer, and furnishes various particulars which, from the con- 

 tracted state of his individuals, were unobserved by Dr. Leach. He 

 also adverts to the statement made by that able zoologist, that 

 in this species all the internal organs are essentially the same as in 

 Octopus : and remarks that Arg. Mans, like Arg. Argo, recedes from 

 the naked Octopods and approaches the Decapods in the structure of 

 the branchial hearts, which are provided with a fleshy appendage, 

 in the form of the appendages of the vena cava, which are shorter 

 and thicker ; and in the relative position of the lozenge-shaped ink- 

 bag, which is not buried in the substance of the liver, but lies in its 

 anterior concavity : the inferior salivary glands are also relatively 

 smaller. The following differences, as compared with Octopus, oc- 

 cur in other internal organs which adhere to the tj'pe of structure 

 that characterizes the Octopodous tribe of the DibrancMata : the 

 laminated pancreatic bag is of a triangular form, and not spirally 

 disposed ; the two o^^ducts are devoid of the circular laminated 

 glands which surround them in Octopus about the middle of their 

 course ; they are also disposed in foxrr or five convolutions as they 

 pass behind the roots of the brancMce ; and they terminate at a rela- 

 tively greater distance from the base of the funnel. 



Mr. Owen then describes various portions of the internal struc- 

 ture of Argonaut a ; and especially its brain, its principal nervous 

 cords, and the lateral muscles, here at their minimum of develop- 

 ment, which attain in Nautilus, as the muscles of attachment to the 

 shell, so enormous a size. 



The eggs are in nearly the same state of development as those 

 which have been described by Mr. Bauer and by Dr. Roget ; and 

 consequently afforded no conclusive proof as to the nature of the 

 connexion of the animal with the shell. In one of them, from the 

 form of the opake body contained within it, Mr. Owen for a moment 

 entertained the idea that the nucleus of the real shell might be 

 found : on tearing open, however, the external tissue, the contained 

 substance turned out to be nothing more than the yelk, separated 

 by an intervening stratum of clear fluid from the transparent mem- 

 hrana vitelli ; and the whole substance of the opake mass separated 

 into the flakes, granules, and globules of oil, of which the vitellus is 

 usually composed : there was not a trace of any consistent parts of 

 an embryo, nor the slightest particle of calcareous matter. 



Mr. Owen concludes his communication by a tabular view of the 

 Cephalopoda, exhibiting the external and internal characters common 

 to the entire class ; those of the several orders and families com- 

 prised in it ; and the names of the genera included in each family. 



March 8. — Mr. Ogilby read a paper, entitled " Observations on 

 the opposable power of the Thumb in certain Mammals, considered as 

 a zoological character : and on the Natural Affinities which subsist 

 between the Bimana, Quadrumana, and Pedlmana." 



