187 
under the genus Spelerpes. For the purpose of studying the pharyngeal 
mucous membrane the pharynx was dissected out from the specimen 
shown in Fig. 1, opened along the mid-dorsal line and pinned back 
(Fig. 5). The only indication of a glottis was a slight puckering of 
the mucous folds about a certain region, 
a, where a little depression is visible. 
The extreme depth of this depression is 
seen in Fig. 2. In my former paper on 
lungless Salamanders, in referring to 
Plethodon I wrote that “die Glottisein- 
stülpung ist kaum von den anderen 
Schleimhautfalten zu unterscheiden” and 
stated that it was more marked in Des- 
mognathus. It seems now that the rudi- 
PIETHODOoN GLuTINOSUS. 
Senay StI hia toi ake 
Fig. 5. Pharynx of Plethodon glutino- 
sus, opened along the mid-dorsal line and pinned 
back to show its internal folds. «a Glottis region. 
5 Oesophagus. c Stomach. 
mentary glottis invagination is shown about equally in the two genera, 
the reason of my former conclusion being that the series used, which 
was the one referred to at the beginning of this description, as the 
one made from the piece cut out, did not extend far enough anteriorly, 
since the invagination is unusually high up. It is always very difficult 
to prove that a thing does not exist and in this investigation I have 
made my series whenever possible extend in both directions far be- 
yond the possible limits of larynx-rudiments. 
In this genus in the region of the glottis fold a very thin sheet 
of striated muscular fibres is spread out over the pharynx ventrally. 
These were overlooked in the first dissection, and seen first in the 
serial sections of P. cinereus (Fig. 2). Later on I succeeded in demon- 
strating them in a dissection of P. cinereus. ‘They consist of very 
fine fibres, meeting in the middle line and diverging anteriorly. They 
lie directly upon the wall of the pharynx and beneath the hyoid ap- 
paratus. They do not seem to be present in the other genera. A 
farther reference to Fig. 5 will show that the oesophageal region is 
distinctly marked by the character of its folds which are very narrow, 
parallel with each other, and run for the most part along its entire 
length (Fig. 5 6). The outside of this region is quite densely pig- 
mented, especially dorsally. The stomach begins quite abruptly, the 
change being shown internally by the change in the character of the 
mucous folds (Fig. 5 c). 
