836 The American Naturalist. [October, 
I have seen of this species only one specimen, which is an adult male. 
The colors of the female may be expected to be somewhat lighter. I 
have dedicated it to Mr. Jno. Van Denburgh, of San Francisco, an 
able writer on herpetological subjects.—E. D. COPE. 
Modification of the Brain during Growth.’—1. One of the most 
marked changes of the embryo brain is the formation of the great bend 
near its middle, giving rise to the cephalic fexure. The cause of 
the bend is unknown. After it is formed, the early appearance of 
optic fibers and those of the posteommissure and supracommissure tends 
to produce a comparatively fixed portion at this bend as shown by 
measurements of parts of the brain in soft shelled turtle and the cat. 
The later developing parts produce secondary changes in the form of 
the brain tube as the embryo takes on the specific characters of the 
adult. 
2. The pons bend of embryo mammals is a feature of the brain of 
many non-mammalian embryos which do not possess a pons, and in 
specimens examined is associated with and seems to be due to the early 
and enormous development of the Gasserian ganglion and its union 
with the brain by the fifth nerve. Later these parts are overshadowed 
by the growth of other parts and the pons bend becomes obscure. 
3. In the cat the pons bend is exaggerated by the formation of a 
great fist shaped mass of cells at the surface on each side of the meson. 
This mass of cells is continuous with a conspicuous layer of cells which 
extends upon the surface to the union of the solid wall of the oblongata 
with the membranous roof or tela. This layer and cell mass seem to 
be proliferations such as His and Herrick have described as occurring 
at the union of a solid wall with a membrane. Later these cells are 
covered by pons fibers. 
4. In the soft shelled turtle and the cat, early stages show clearly 
that the prosotela, the membrane included by the edges of the rima in 
the cerebrum, is a continuation of the membranous roof of the dien- 
cephal, such that if the brain were plastic the continuation of each side 
could be brought to occupy the dorsal surface of its cerebrum. A con- 
dition would thus occur which is comparable with the actual condition 
found by Wilder in Ceratodus. It may be of value in the further 
determination of homologies between the brain of fishes and mam- 
mals, as in fishes the membranous roof of cerebrum and diencephal is 
continuous. 
2 Abstract of paper read before the Amer. Asso. Ady. Sci., Aug. 24, 1896. 
