88 OSBORN. [VoL. Il. 
bundle immediately below the anterior commissure; as we ascend, they multiply and 
form a crescent in the anterior median columns; at the exit of the vagws they sep- 
arate into two strands, one, dorsal, below the sulcus centralis, the other, ventral, 
in the anterior columns; the ventral strands cross and disappear between the exit of 
the oth and 8th nerves, entering large ganglion cells. The dorsal ascend to a higher 
level without apparently crossing; they are continuous with and appar- 
ently constitute the main portion of the posterior longitudinal 
fasciculus. 
The Auditory tract of this fasciculus closely adjoins the dorsal Miillerian fibres, 
but may be distinguished from them by the slightly smaller diameter of its fibres; it 
is clearly distinguished opposite the exit of the roth pair! and on all the higher 
levels; this leads me to the conclusion that this portion of the posterior longitudinal 
fasciculus is an ascending auditory tract apparently distinct from 
the Millerian fibres. This further throws in doubt the supposed connection 
between this fasciculus and tract. 
4°. Wilder upon the brain of Ceratodus. This description is macro- 
scopic. In Ceratodus, like Protopterus, and unlike the lower Urodela, the ventri- 
culus communis is very small. As in the Urode/a there is a large supraplexus. 
The olfactory lobes, unlike those of Protopterus and the Amphibia, are pedunculated 
instead of sessile. The anterior commissure is mentioned, but the corpus callosum is 
not observed. Finally, an important distinction is seen in the fact that the extension 
of the hemispheres (secondary forebrain) is vedva/ from the primary forebrain both 
in Ceratodus and Protopterus, instead of directly anterior, as in the Amphibia. 
I may express here my indebtedness to Professor Wilder for much of the termi- 
nology which I have adopted from his papers, and my regret that he has found it 
necessary to change his former terms in so many instances. 
5°. Stieda’s observations upon Axolotl include several points in which, 
if correctly described, this genus differs from Crvptobranchus. 1. Opposite the exit 
of the 12th nerve, on either side of the sulcus centralis, is a large Mauthner 
fibre, exactly as in Petromyzon. I think these fibres are not present in Cryffo- 
branchus. 2. The ascending Vagus, or fasciculus solitarius, while arising in 
the same manner as in Cryftobranchus, is given off with the exterior roots, the 
Glossopharyngeus portion, instead of with the posterior. 3. A portion of the pos- 
terior longitudinal fasciculus makes its exit with the 8th pair, but is desig- 
nated by Stieda as a portion of the Facial-Trigeminal system. This probably cor- 
responds to the bundle which I have finally referred to the 8th nerve, Fig. 15, VII.- 
VIII. 3, 4. Another important observation is that a portion of this same fasciculus 
enters the Trigeminus. I am inclined to doubt this, as it has no parallel elsewhere, 
and it would be easy to mistake this for the posterior bundle which I have observed 
uniting with the descending trigeminus (see 54%, Fig. 17). 4. Stieda describes 
the ascending trigeminus as sezsory, probably from its relations in human anatomy; 
it is true this tract is first found in the sensory column of the cord, but it subsequently 
lies in the motor region and is reinforced by motor cells. It probably consists of 
mixed fibres. 
Stieda’s and Képpen’s observations upon the brain of Rana. It 
is difficult to give a critical review of Stieda’s results, first, because from the limitations 
1] regret that none of the figures represent the relations of this tract to the Miillerian fibres with 
perfect accuracy. I am not sure that this tract can be clearly distinguished at the level of the r2th 
pair, as represented in Fig, 11, 
