SEELYE: CIRCULATORY SYSTEM OF DESMOGNATHUS. 345 
aorta and giving off at each vertebra a ramus dorsalis and a ramus cos- 
talis with extremities terminating in the skin. 
5. A small arteria cutanea magna branching from a. subclavia. 
6. An arteria pulmonalis, really the fourth arterial arch, sending 
one branch to the skin and passing along the lateral surface of the 
stomach to anastomose with the a. gastrica. 
7. A large vena cutanea magna, with a branch, vena cutanea parva, 
opening into the ductus Cuvieri. 
8. A vena subclavia opening separately into the ductus Cuvieri. 
9. A vena oesophagea. 
10. Two venae caudales instead of one. 
11. An arteria pharyngea. 
The capillary distribution in Spelerpes, as worked out by Bethge, 
may be summed up as follows: in the skin the capillaries are directly 
beneath the epidermis, they surround the glands all over the body, and 
are accompanied by pigment. The width of these cutaneous capil¬ 
laries was from 24 to 30 micra in Spelerpes, while in Triton they 
measured from 12 to 16 micra, and in Salamandra only from 7 to 12 
micra. In the esophagus Bethge speaks of a rich network of blood 
vessels, and shows drawings of sections through the esophageal wall 
in which the capillaries lie among the epithelial cells, while in stomach 
and intestine they reach only to the epithelium. In Salamandra the 
network is especially rich in the region of the glottis, and in Spelerpes 
there is an area rich in capillaries where a glottis may once have 
been. The capillaries of the pharynx and mouth of Spelerpes are 
described by Bethge as bearing little swellings or diverticula so that 
they look almost like stems with berries on them. He refers to a simi¬ 
lar appearance noted by Langer in 1867 in the frog. 
Bethge makes these general conclusions from his studies of the dis¬ 
tribution of blood vessels in Spelerpes: that cutaneous respiration 
must be very important in lungless salamanders; that although the 
capillaries are nearer the surface in mouth, pharynx, and esophagus 
and are diverticulated, still the much greater extent of the skin capil¬ 
laries equalizes this,- if it does not overbalance it; that the fact that 
some tissues take a large amount of their oxygen directly and solely 
from blood coming from the skin speaks for the importance of cuta¬ 
neous respiration; and that Camerano’s statement that cutaneous 
respiration is unimportant in the case of Spelerpes fuscus must be con¬ 
tradicted; both kinds of respiration are necessary to the life of this 
animal. 
