310 



ANATOMY OF VERTEBRATES. 



nerves progressively increase in length in the Turtle, Iguana, and 

 Crocodile. The distribution of their fibres upon the vascular 

 pituitary membrane, supported by the turbinal cartilage, is well 

 displayed in a Hunterian preparation of the Turtle. 1 



The optic nerves, corresponding in size with that of the eyes, 



206 



i erel iral, anterior spinal, and sympathetic nerves, Python. Liv. 



are smallest in the fish-like Batrachians. They arise from the 

 optic lobes, fig. 192, o, thalami, and optic tracts, ib. d, and blend, 

 by a few decussating laminae, into a chiasma, ib. b, before diverg- 

 ing to the visual organ : their course is shown, in the Python, at 

 The position of the ' third ' or oculo-motor nerve is 



fig. 188. 



1 xx. vol. iii. p. 89, nos. 1532, 1533. 



