and Siruetum of the Proteus Angurnus . 9B 
small cleft or chink, the margins of which do not rise above the 
surface, nor possess a cartilaginous structure. This very small 
chink or glottis, as it may be called, communicates with a very 
short canal, which proceeds backwards above the heart, between 
the pericardium and pharynx. This canal exteriorly, and on 
the side next the heart, is furnished with two very fine muscu- 
lar expansions, the fibres of which springing from the median 
line of the canal itself, are disposed like the beard of a pen, and 
directed back towards the branchial arches. The office of this 
very subtile muscular substance is, doubtless, that of dilating the 
canal, and opening the glottis. The canal itself, before getting 
beyond the heart, opens, by a semilunar aperture, which lias car- 
tilaginous margins, into a large conical cavity, Plate VII. Fig. 2. 
From this funnel-shaped cavity, are continued two membranous 
canals, which, keeping the stomach between them, descend towards 
the tail : but before reaching the lower-third of the trunk, they 
begin to dilate, and by degrees expand, so as to acquire the form 
of two small flasks ; the left descending a little lower than the 
right. These two canals are attached to the spine, by duplica- 
tures of the peritoneum, in which, through their whole length, 
they are involved. The two little flasks or bladders have no 
cells nor partitions internally, but arp perfectly smooth mem- 
branes. Were it possible to dilate the two canals to the size of 
the bladders in which they terminate, these organs would then 
acquire very exactly the form of the lungs of the salamander. 
The two bladders are situated one on each side of the abdomen ; 
that of the left side is represented in Plate VII. Fig. I., and also 
the narrow canal leading to it. In protei that have been some 
time in spirits, the canals become entirely closed and quite imper- 
vious to air ; but in those recently dead, the bladders are easily 
dilated by air blown through the canals. 
The authors having observed, that, when a living frog or sala- 
mander is laid on his back, the abdomen then opened, and its 
walls fastened back, the lungs, during the struggles the animal 
makes, sometimes dilate and contract for a certain time, were 
desirous of ascertaining, by a similar experiment, if the small 
portion of air which the proteus takes into the mouth found its 
way into the two little bladders above described. A proteus 
g 2 
