CEREBRAL HOMOLOGIES. 



41 



nates in a " suboesophageal " mass, divided into two portions 

 and supplying the parts corresponding with those in Verte- 

 brates which send and receive their nervous influences through 

 the "medulla oblongata" (macromyelon) and the "spinal 

 cord" (myelon). 



The dibranchiate homologue of the supracesophageal gan- 

 glion moreover supports a part of the vertebrate cerebrum, 

 less manifestly, if at all, shown in other Invertebrates. It is a 

 superposed mass of a whiter colour than the rest of the en- 

 cephahc centres, with an indication of a division into a lateral 

 pair of lobes, and, in Sepia, presenting a subtriangular form 

 with the apex anterior. From the deeper-seated part of the 

 " supracesophageal " mass are sent off, besides smaller fila- 

 ments, a pair of nerves, or " crura," which converge and are 

 lost in a more anterior ganglionic mass — the " ganglion sus- 

 buccal," or the superoral gangUon, of Cuvier — which distri- 

 butes nerves to the delicate membranous folds and processes 

 developed from the interspaces of the cephahc arms, and to 

 the plicated and papillose lips which surround and project 

 anterior to the beak, and which soft and lubricous parts we 

 may reasonably suppose to receive from their supracesophageal, 

 or cerebral, centres the faculty of judging of the odorous qua- 

 lities of the substances to be seized by the beak. 



From the anterior portion of the larger " suboesophageal " 

 mass are sent off nerves to the rasping and gustatory organs 

 within the mouth, and the larger nerves which supply the 

 eight cephahc acetabuliferous arms and tentacles. From the 

 posterior division of the suboesophageal mass are sent off the 

 moto-seusory nerves of the trunk already noticed, and also 

 visceral nerves*. 



In the Tetrabranchiate Cephalopods the foregoing primary 



* ' Anatomy of the Pearly Nautilus,' 4to, 1832, p. 38, pi. 7. %• 3, 



