OF THE COIS-AEIO-HTPOPHTSIAL TRACT. 145 



The suboesophageal mass or ganglions in Cepbalopods send off 

 the nerves to the prehensile arms, and are in communication with 

 the viscera, the muscles, and the soft parts of the trunk. Moreover, 

 in Vertebrates this epencephalic homologue is ia direct nervous 

 communication with the organ o£ hearing {h, figs. 7 and 8). The 

 fore brain, on the opposite side of the gullet in the Cephalopod 

 (fig. 7, a), supj)lies the nervous masses subservient to the large 

 and complex organs of vision, and also parts vs^hich may exercise 

 the sense of smell. But, if the suboesophageal mass, h, and the 

 moto-sensory neural continuations of the trunk, t, be, in the Ce- 

 phalopod, homologous with those in the Insect (fig. 3, i) and Crus- 

 tacean, the ground on which I predicate, in the Articulate, of the 

 neural aspect of the body, that it answers to that commonly 

 called " dorsal " in Vertebrates, is applicable also to the Mollusk, 



Therefore the part which Cavier indicates in his diagram, 

 and terms brain (" cerveau," a), is not a true criterion of the 

 back ("dos"); it occupies in the Cephalopod and other cere- 

 bral Invertebrates the aspect of the belly, or tract of the body 

 which I term "haemal," and which is called the ventral or under 

 part. 



To be sure this cannot be predicated of the brain (" cer- 

 veau," a) of the quadruped. And why ? Because the alimentary 

 tract and outward anterior opening which, would demonstrate its 

 holding a position opposite to that of the rest of the nerve- 

 centres has been atrophied, and exists as an arrested residuary 

 embryonal part (figs. 3 and 8, 7-8). It is the superadded respi- 

 ratory organization in connection with the oral end of the alimen- 

 tary canal and the concomitant opening of the mouth in a new 

 position, in the Vertebrate, which turns the cerebrum to the 

 side occupied by the rest of the nerve-centres — in other words, 

 to the neural aspect of the body. Individual development being 

 achieved, the Vertebrate becomes " hsemastomous," the Inverte- 

 brate remains " neiirostomous." 



At the embryonal stage of the higher subclass at which the 

 primary mouth was continued across the brain, the " D"nity of 

 Plan " between the Vertebrate and Invertebrate animal was 

 exemplified; and tbat " unity " is, in the main, preserved under 

 the recognition of the neural and haemal aspects of the body, as 

 shown in figs. 2 and 3, representing the Articulate and Vertebrate 

 types. 



