1896.] Zoology. 831 
forms that have been mentioned, as well as in other members of the 
class Batrachia, the sinus venosus opens distinctly into the right auricle 
and the pulmonary vein into the left. 
Let us now compare the heart of a lungless salamander (Fig. 2.) with 
the one just described. The four parts, auricles, ventricle, bulbus arte- 
riosus and sinus venosus are clearly recognizable and, superficially 
examined, present nothing unusual; it is only when the cavities 
are opened that the differences between the two hearts become 
apparent. One of the first things to attract attention is the left auri- 
cle. In the lungless forms examined, it is much smaller in comparison 
to the right than in Diemyctylus, for example, and no pulmonary vein 
was found opening into it. 
The auricular septum has only one opening through it, or perhaps, 
more correctly, it extends only part way across the cavity, but this 
aperture in the septum isso large (Fig. 2, 9.) that it is believed the com- 
munication between the two cavities is more free than even in Necturus. 
Just what function or functions the septum may have in these lungless 
forms, it seems to me, is not quite clear. Thatit has but little, if any use, 
is indicated by the way the sinus venosus opens into the auricles. In 
place of opening into the right auricle only, asin the forms having lungs, 
it opens more freely into the left auricle than into the right. If the ven- 
tral parietes of the heart be removed, one can look directly into the 
opening of the sinus venosus from either of the auricles, but more 
directly into it from the left than from the right, for when seen from 
the latter, one must look through the large opening of the auricular 
septum, Fig. 2,9. In salamanders with lungs, each auricle opens in 
common into the ventricle with about equa] freedom of communication, 
whereas in the lungless forms the right auricle is in more direct com- 
munication with the ventricle than is the left. 
Judging from the above facts, i. e., the way the sinus venosus opens 
into the auricles, the freedom with which the auricles communicate 
with each other, and the way the auricles communicate with the ven- 
tricle, it would seem as if the heart of the lungless salamanders, functi- 
onally, was only bilocular in place of being trilocular as in the rest of 
the Amphibia. Morphologically, of course, it is trilocular, but whether 
it is so physiologically seems to me doubtful. 
The heart of 8 lungless species have been examined by the writer, 
and so far as was made out, all of them agree closely with the descrip- 
tion as given above. The probabilities are that in all the lungless 
forms similar conditions of the heart will be found. Up to the present 
time 17 species and sub-species, either wholly without lungs or with only 
