12 CEREBRAL HOMOLOGIES IN TERTEBRATES AND INVERTEBRATES. 



those liomologies may be predicated of the modifications of the 

 brain in the Articulata. 



So plain, so obvious, indeed, seem to me the grounds for such 

 homologies, that I should have shrunk from urging them before 

 my fellow-labourers of this Society were not views very analo- 

 gous to the restricted ones of Cuvier maintained and asserted by 

 the accomplished and experienced comparative anatomist, espe- 

 cially of Invertebrate animals, in the United States, to whose 

 valuable Monograph * I have already referred. 



I gladly, however, welcome the alliance of my Master in predi- 

 cating corresponding parts of the nervous centres in the whole 

 series of brain-possessing animals, so far as he felt himself justi- 

 fied to go. And I avail myself of this concordance to define, 

 agreeably with our common views, the aspects of the body in the 

 adult Cephalopod, but in the terms which have been suggested 

 by conclusions as to the essential conditions and wide extent of 

 a possible predication of neural homologies. 



The side of the body of a Cuttlefish or Squid denoted by the 

 " neuroesophageal " (" suboesophageal" so called) brain-part, 

 with the chief nervous extensions therefrom along the trunk, is 

 the " neural aspect," its superficies the " neural surface." The 

 side of the body to which the " hsemoesophageal " (so-called 

 " supraoesophageal ") brain-part has been turned by the course 

 of the gullet is the " haemal aspect ; " its superficies is the " haemal 

 surface." The "narrow space enclosed by the arms, which con- 

 tains the mouth," together with the entire acetabular surface of 

 those cephalic arras, is the anterior or " oral surface," answering 

 to that so termed in all other Invertebrates, as is the homologous 

 part in all Vertebrates. The opposite end of the body, with its 

 appended fins, is the posterior or caudal end; what is usually 

 called the upper surface in adult Cephalopods, as in all lower 

 MoUusks and in Articulates, is the " haemal one ; " the opposite 

 surface is the " neural " one. As here defined, and as illustrated 

 and named in a former contribution to the Society f, there can 

 be at least no doubt as to the answerable aspects and surfaces in 

 any Invertebrate possessing comparable centres and cords of 

 the nervous system, with comparable centres, or hearts, of the 

 vascular system. So the hteart in man indicates the " haemal " 



* Ante, p. 2. 



t Joui-nal of the Linnean Society (Zoology), January 1882, p. 131, figs. 2, 3, 

 7,8. 



