ANIMAL KINGDOM. 249 



and not at the extremity of tentacula. This head is in Clio 

 crowned by six very long retractile conical tentacula, dis- 

 posed in two lateral groups of three each, which, when re- 

 tracted, give to the head an appearance of being formed 

 of two great tubercles. Finally, the vertical mouth in 

 Clio resembles in a very remarkable manner that of the 

 Cephalopoda as to position. But notwithstanding these 

 and other affinities, the general structure of the animal 

 has "undergone an almost thorough alteration; thus the 

 head, which in the Mollusca was so indistinctly separated 

 from the body, is now not only, well defined, but in the 

 cartilaginous ring which envelopes the brain presents the 

 first vestige which we have yet seen of a skull. Hitherto 

 we have seen but few animals endowed with the organs 

 of sight ; and when the eyes existed, or rather when we 

 supposed these organs to exist, we have found them merely 

 black points affording no trace of that peculiar organization 

 which we are led from analogy to conceive necessary for 

 the purpose of vision. But now we are arrived at animals 

 possessing eyes, constructed on the same plan and hardly 

 inferior in their construction to those of the most perfect 

 Vertebrata. Hitherto we have seen no traces of an ear; 

 but in the Cephalopoda the celebrated Scarpa has detected 

 the sense of hearing, though the organs destined for that 

 purpose are in their very simplest form. It would appear 

 that neither in the Cuttlefish any more than in the Mol- 

 lusca are there any organs peculiarly adapted for smelling 

 to be discovered ; but since they all, as we learn from the 

 study of their manners, undoubtedly possess the sense, 

 perhaps the conjecture of Cuvier is not improbable, namely, 

 that the whole skin may be the seat of smell ; from its 

 resembling so much a pituitary membrane. 



