13 



always a correspondence in size between the two. Further, it was 

 noted that the eggs of the Argonaut, when developed, produced a 

 shell-less Cephalopod with rudimentary eyes and arms, but that this 

 same naked infantine Cephalopod in a few days became coated with 

 a Nautilus-like shell. These facts, three years later, were also de- 

 monstrated before the Zoological Society in a paper by Professor 

 Owen, illustrated by specimens furnished by Madame Power. 



The questions relating to the Argonaut's sails, and the true nature 

 of their owner, already briefly mentioned, do not comprehend the 

 extent of the difficulties in deciphering this denizen of the ocean, 

 which investigation has suggested. The learned in the Cephalopoda 

 some time since noting that the Argonauts hitherto found, appeared 

 to be females, asked where were the males, and in consequence pro- 

 pounded two theories, one, — that the male avoids public places, 

 and so keeps to the bottom of the sea, and is unknown ; the other 

 that the male is a mere worm-like creature (Hectocotyle *) an inch or 

 so long, without a shell, which being very feeble, for safety's sake 

 makes the Argonaut's abode its own, as tenant-at-will, rather than 

 as freeholder, — theories which have failed. 2 



Resuming then the preceding observations, it will be found we 

 have viewed the Cephalopods as divisible into two large groups, — 

 first, the two-gilled, including the Cuttles with eight arms, the Squids 

 with ten arms, both with internal supports, the Argonaut with an 

 external, and the Spirula with a partly internal shell ; and the second, 

 the four-gilled, containing the Nautilus. 



These divisions, treated more in detail, would have resolved them- 

 selves into numerous families and genera — a long series of names, 3 

 with which I will not now weary you, 



If the Geologists' Association were content with the knowledge 

 of such beings as can be found upon our own shores, or may be met 



1 See paper by Prof. Kolliker of Zurich, published in Trans. Linneau Soc., vol. 

 xx., p. 9, 1851. 



2 Dr. Miiller in the Annales des Sciences Naturelles, t. xvi., doscribed, in 1S52, 

 the male Argonaut as being a creature of very small size, shell-less and Cephalopodic 

 in shape, and also explained the true nature of the Hectocotyle. 



3 In Appendix I., at the conclusion of this paper, will be found a complete list of 

 the families of the recent Cephalopoda, with a brief description of each genus; and in 

 Appenlix II. the same with respect to the fossil Cephalopoda; Appendix III. 

 gives the range in geological time of the latter group. 



