344 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
tively smaller part in the case of the animals with lungs. In other 
words the lungs perform more of the respiratory function in the lunged 
forms than do the bucco-pharyngo-esophageal parts in the lungless 
forms, although the function of the latter parts is shown to be an im¬ 
portant one. 
In general the few conclusions that can be drawn from these inter¬ 
esting but necessarily imperfect and limited experiments on the osmotic 
function of the skin and on the respiratory activities of the animals 
themselves, are that contrary to Camerano and in accordance with 
Bethge’s view, cutaneous respiration plays an important part in the 
life of lungless salamanders, and that the respiration carried on in 
mouth, pharynx, and esophagus must also be of high importance. 
The Circulatory System. 
When my dissections and drawings of the circulatory system of 
Desmognathus were nearly completed, Emil Bethge published, in 
1898, an article entitled “Das blutgefasssystem von Salamandra macu- 
lata, Triton taeniatus, und Spelerpes juscus; mit betrachtungen liber 
den ort der athmung beim lungenlosen Spelerpes juscus . ” This 
work included, besides a study of the anatomy of the main blood ves¬ 
sels of these animals, an account of the distribution of the capillaries 
in the skin, pharynx, and esophagus. It therefore covered some of 
the ground that I had been investigating, but the lungless form which 
Bethge studied for the purpose was a different one. Spelerpes juscus 
is a much larger salamander than Desmognathus, but Bethge did not 
try to work out in detail the course of as many veins and arteries as I 
have done in the case of Desmognathus. The comparison with his 
work thus afforded was, however, extremely interesting and of great 
service to me. 
The following is a recapitulation of the important peculiar points in 
the circulatory system of Spelerpes juscus as worked out by Bethge:— 
1. The total absence of a vena pulmonalis. 
2. An arteria maxillaris externa arising from the second arterial 
arch on each side and branching to upper and lower jaw. 
3. An arteria occipitalis branching into the tissue of the roof of the 
mouth and sending one branch to the eye. 
4. Two arteriae vertebrales collaterales, communicating with the 
