584 CEPHALOPODA. 



that the merit belongs of having first indicated the existence of this 

 curious arrangement ; but while the illustrious Neapolitan naturalist 

 regards it as being simply a large venous sinus, Milne-Edwards looks 

 upon it as being the visceral cavity itself, lined with peritoneum, as 

 in the higher animals, into which the blood is received, and wherein it 

 bathes directly the pharyngeal mass, the salivary glands, the stomachs, 

 and the other principal viscera. In the Cuttle-fish (Sepia) and in the 

 Calamary (Loligo), the above peculiarities met with in the " Poulpe " 

 do not exist, so that there is a remarkable accordance between the in- 

 ternal structure of these Cephalopods and the zoological characters 

 furnished by the number of their cephalic appendages. In those genera 

 furnished with only four pairs of arms the venous system is semi- 

 lacunose in its character, whilst in the ten- armed races it is entirely 

 vascular throughout the abdomen, although it still presents a lacunose 

 character in the cephalic region. 



(1564.) In the nervous system of the CEPHALOPODA we may naturally 

 expect to find not only a superiority in the development of the nervous 

 centres, as compared with the condition of these important masses in 

 the lower Mollusca, but some indications at least of an. approximation 

 to that arrangement so eminently characteristic of the vertebrate di- 

 vision of the animal world, to the confines of which we are now gra- 

 dually approaching ; more especially as, in the activity of the move- 

 ments of these creatures, and in the increased perfection of their senses, 

 we have abundant evidence of the elevated position assigned to them 

 when contrasted with other mollusks of less carnivorous and rapacious 

 habits. 



(1565.) The nervous ganglia from whence the muscles and viscera 

 derive their supply are still numerous and widely scattered ; but their 

 size is considerable, and proportioned to the importance of the organs over 

 which they preside. It is to the encephalic portions of the nervous 

 system, however, that we must principally turn our attention if we 

 would rightly estimate this part of their economy; and these, we at 

 once perceive, have in the class before us attained to such magnitude 

 and importance that they emulate, no longer dubiously, the brain of a 

 fish, with which it is not difficult to compare them. 



(1566.) In a Cephalopod the encephalon (for so we now may truly 

 call it) is enclosed, as has been already noticed, in a distinct cartila- 

 ginous skull, which embraces it on all sides and defends it from injury. 

 The capacity of the cranial cavity, however, is more than sufficient to 

 contain the brain ; and, as is the case in fishes, the interspace is filled 

 up with a semigelatinous substance. The brain, moreover, still forms 

 a ring, through which the oesophagus passes ; so that we might with 

 propriety preserve the terms supracesophageal and infracesophageal 

 ganglia, were these parts not now become so intimately united to each 

 other that they seem fused into a single mass (fig, 294, a, 6), from 



