EXPLANATION OF PLATE II. 



The Figures in this Plate represent the principal forms of the Nervous Centres in diffe- 

 rent classes of animals. The 1st is copied from a Memoir by M. Blanchard ; the 2d, 

 3d, and 4th, from Mr. Newport's delineations ; the 5th to the 13th from the work of M. 

 Guillot on the Comparative Anatomy of the Encephalon in the different classes of Verte- 

 bvata ; and the last two from the work of M. Leuret on the same subject. 



Fig. 1. Nervous System of Solen; a, a, cephalic ganglia, connected together by a trans- 

 verse band passing over the (Esophagus, and connected with the other ganglia 

 by cords of communication ; b, pedal ganglion, the branches of which are 

 distributed to the powerful muscular foot ; c, branchial ganglion, the branches 

 of which proceed to the gills d, d, the siphons e, e, and other parts. On some 

 of these branches, minute ganglia are seen ; as also at/,/, on the trunks that 

 pass forwards from the cephalic ganglia ( 852). 



Fig. 2. Nervous System of the Larva of Sphinx ligustri; a, cephalic ganglia; 1-12, 

 ganglia of the ventral cord ($ 856). 



Fig. 3. Thoracic portion of the Nervous System of the Pupa of Sphinx ligustri; a, b, c, 

 three ganglia of the ventral cord ; d, d, their connecting trunks ; e, e, respira- 

 tory ganglia ( 862). 



Fig. 4. Anterior portion of the Nervous System of the Imago of Sphinx ligustri; a, cepha- 

 lic ganglia ; b, b, eyes ; c, anterior median ganglion, and d, d, posterior lateral 

 ganglia of stomato-gastric system ; e, /, large ganglionic masses in the thorax, 

 giving origin to the nerves of the legs and wings ($ 863). 



Fig. 5. Brain of the Perch, seen from above ( 869). 



Fig. 6. The same, as seen from below. 



Fig. 7. Interior of the. same, as displayed by a vertical section. 



The following references are common to the three preceding, and to the succeeding 

 figures. 



a, rt, Olfactory lobes or ganglia. 



b, b, Cerebral ganglia or Hemispheres. 



c, c, Optic lobes. 

 </, Cerebellum. 

 e, Spinal Cord. 

 /, Pineal gland. 



g, Lobi inferiores (their precise character not determined). 

 A, Pituitary body, 

 t, Optic Nerves. 



