836 The American Naturalist. [October, | 
which have been examined; as to the Tortricide [Ilysiide], 
there are apparently species with two lungs (T. zenopeltis) 
[=-Xenopeltis unicolor], and others with a single lung (T. 
scytale) [=Ilysia scytale]. Among Eurystomata, all the Per- 
opoda (Boa, Python, Eryx) possess apparently two lungs. 
The Calamarina that have been investigated have one lung. 
Among Colubrina and Glyphodonta, there are great varia- 
tions. All the Coronelle of Schlegel possess, according to 
Schlegel, a single lung. I find the lung single in Rhachiodon 
séaber [ Dasypeltis]. Tropidonotus natrix [ Natrix vulgaris] has a 
very small rudiment of a second lung. Coluber [Spilotes] vari- 
abilis possesses, according to Schlegel, the rudiment of a second 
lung. According to the statement of Meckel, this rudiment is 
common in Coluber. The Xenodons have, according to 
Schlegel, a single lung (X. severus and X. rhabdocephalus). In 
Heterodon I find a rudimental second lung. The Lycodons, 
according to Schlegel, possess a single lung; as also do Psam- 
mophis and Homalopsis. In Dendrophis colubrina Schlegel 
found the rudiment of the second lung. In Dipsas, according 
te Schlegel, there are variations; but he states that D. multi- 
maculata, D. levis and D. annulata [Sibon annulatum], have but 
one lung. The Achrochordina have but one lung. Among 
Hydrophide I found in three species of Hydrophis the lung- 
sack simple. Meckel states that Platurus has a very small 
rudiment of a second lung. Among the remaining poisonous 
snakes there is an insignificant rudiment of the second lung 
in the Elapina and Crotalina; while the Viperina possess an 
entirely simple lung.” 
An examination of about one hundred and fifty species of 
nearly all types yielded the following results. 
The snakes with rudimental posterior limbs (Peropoda), 
show in the character of their lungs, what they show in the 
rudimental limbs themselves, and in the hemipenis, the near- 
est relationships to the Lacertilia. They possess, with an 
exception to be noted later, two well-developed lungs, one of 
which is larger than the other. The smaller lung lies to the 
right side and ventrally, while the larger one lies to the left 
side and dorsally. In some species the dorsal and ventral 
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