NOTE ON THE DEVELOPMENT OE AMPHIBIANS. 313 
in the Amphibia is throughout about the same as I have 
described it for the Lizard. 1 
Figs. 27 h — 30 h show four horizontal sections through the 
head of an embryo of Amblystoma at an age corresponding to 
that of fig. 18. These sections show the nerve-fibres of the 
brain at a more advanced period than that above described. 
Of these sections, 27 h is cut nearest the dorsal surface of the 
head, and on the left side passes above the lateral band of 
longitudinal fibres ( L . F .) in the region of the secondary cranial 
flexure just in front of the ear. On the same side of the 
section the lateral band in the hind-brain is seen to be con- 
tinuous with the lateral band in the mid-brain ( L F.). In front 
of the mid-brain is seen the posterior part of the cerebral 
hemispheres. The next more ventral section (28 h) passes 
through the*thalamencephalon and through the fold which 
separates the infundibulum (In.) from the hind-brain. In the 
hind-brain may be seen the transverse fibres of the ventral 
commissure (T. F.). These are also visible ( T.F .) in section 
29 h, the hind-brain in this section being cut tangentially to 
its ventral convexity. In this same section may be seen on 
the right hand side the connection between the lateral baud 
and those fibres which run dorsally along the corpora striata. 
One part of these fibres forms the anterior commissure as 
above mentioned (fig. 30 h, A. C.) ; while the other part con- 
tinues onward to the region of the olfactory nerve (n. I), and 
here blends with a superficial layer of nerve-fibres, which 
covers the lateral dorsal part of each hemisphere, and extends 
so far upwards and backwards as to appear in section 27 h. 
Fig. 30 u shows the brain in section very near its anterior 
surface. At A. F. may be seen the fibres of the anterior band, 
with the fibres of the optic nerve ( n . II) blending with its 
dorsal edge. At A. C. may be seen the fibres of the anterior 
commissure. Between the thickening of the anterior band 
and the anterior commissure appears the optic groove ( o.g .). 
1 Orr, "Contribution to the Embryology of the Lizard,” ‘Journal of 
Morphology,’ vol. i, No. 2, 1887. 
