. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. CEPHALOPODA. 551 nerve terminates in this ganglion, (v, v, Jig. 226,) from which about twenty branches radiate to the mantle ; but in the Decapoda, in which lateral fins are superadded to the trunk, it pre- viously divides into two large branches. Of these the external alone produces the ganglion from which the sensitive nerves are distributed in a radiated manner, as in the Poulp; the other division (e,fig. 232), after having been joined by a branch (f) from the ganglion, pierces the fleshy substance of the mantle, and
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. CEPHALOPODA. 551 nerve terminates in this ganglion, (v, v, Jig. 226,) from which about twenty branches radiate to the mantle ; but in the Decapoda, in which lateral fins are superadded to the trunk, it pre- viously divides into two large branches. Of these the external alone produces the ganglion from which the sensitive nerves are distributed in a radiated manner, as in the Poulp; the other division (e,fig. 232), after having been joined by a branch (f) from the ganglion, pierces the fleshy substance of the mantle, and ends in a diverging series of twigs appropriated to the muscles of the fin (g). In proportion as the trunk of the Cephalopod is elongated, these branches become more parallel in their course, and dorsal in their position. The anterior part of the mantle is supplied by small nerves, having a distinct origin from the posterior suboesophageal mass, above the great moto-sensitive chords. With respect to the parts of the central axis of the nervous system of the Vertebrata which are represented by the structures above de- scribed, we may reasonably infer from the fact that the suprao2sophageal mass in the Dibran- chiate Cephalopods, especially the posterior division, is principally in communication with, and owes its superior development chiefly in relation to the complex organs of vision, that it is analogous to the optic lobes or bigeminal bodies. For if it be regarded, as Cuvier sup- poses, as the cerebellum of the vertebrate brain, we have then to reconcile the anomaly of this part being the seat of origin of the optic nerves. The constancy, again, of the optic lobes in the vertebrate series, and their priority of develop- ment to the cerebellum, leads naturally to the expectation that these would form part of such a brain as the highest invertebrate animal is endowed with. The smaller portion of the brain of the Poulp anterior to the optic lobes appears to represent an olfacto
Size: 1610px × 1552px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, booksubjectanatomy, booksubjectphysiology, booksubjectzoology
