76 The American Naturalist. [ August, 
merged with its predecessor. In Amphiuma I find no trace of 
any gill bar behind the fourth of the adult. 
Nervous System.—The brain of the larva studied varies 
considerably from that of the adult as described by Osborn. 
The account of the internal structure is reserved until later. 
Externally it is characterized by its shortness and longitudinal 
compression, this being more marked than in any adult Batra- 
chian except that of the Gymnophiona as described by Wald- 
schmidt and Burckhardt. It exceeds in this respect the brain 
of Protopterus as figured by Fulliquet. Asin the latter form 
the cerebral hemispheres are pushed back upon and wedged 
apart by the twixt brain, while behind, the mid-brain and cere- 
bellum are so folded over upon the medulla that the lateral 
angles of the ‘fossa rhomboidalis’ extend nearly to the pos- 
terior lobes of the cerebrum? The brain flexure, however, is 
apparently slight, the primary bend being corrected by a 
secondary one. The cerebral hemispheres are distinct above 
and in front of the lamina terminalis; the olfactory lobes are 
not distinct from the hemispheres. The floor of the twixt 
brain is very short and the infundibulum and hypophysis are 
very broad, the latter being wider than the mid-brain in its 
widest place. The choroid plexus of the anterior ventricles is 
well developed, but calls for no special remark. The cavity of 
the pinealis is still in connection with the cavity of the brain 
and its enlarged distal portion, which reaches nearly to the 
roof of the cranial cavity, is considerably lobed and folded. 
The olfactory nerve arises by a single root,‘ goes laterally 
from the tip of the hemisphere and, in the nasal capsule, divides 
into upper and lower branches which innervate the nasal epi- 
thelium and Jacobson’s organ respectively. 
The optic and oculomotor nerves call for no comment. I 
failed to find the fourth (trochlearis) and the sixth (abducens) 
in my preparations. 
The fifth nerve presents several features of interest. As my 
3Cf. Waldschmidt’s account of the Gymnophionan brain. 
‘Weidersheim formerly thought that the double origin of the olfactory in the Gym- — 
nophiona had great morphological importance, but the studies of the Sarasins and of 
Burckhardt show that such is not the case 
