1889.] Life-History of Choropliilns triseriaUis. 771 
nasal pits formed, the eye-balls beneath the skin, and the auditory 
organs as simple hollow cavities. There is no mouth, only a 
depression where the mouth will be. The " suckers," or " holders," 
are fully developed. 
By the 5 th of April the tadpoles had escaped and were 
swimming about in the pool. The mouth is not yet perforated, 
there are no gill slits, and the gills themselves appear as mere 
buds. It does not appear that they ever become important 
organs. The holders are present, but they seem scarcely as 
prominent as they were in the unhatched young. The larvae are 
thin from side to side, and slenderer than are those of Rana 
vircsccns at the same stage. They are of a yellowish gray color, 
with punctulations of black. It is with great difficulty that, in 
sections, one can make out the cartilaginous lower jaw, the hyoid, 
and one or two branchial arches. 
On the I ith of April the young have reached a length of 7.5 
mm. The body is becoming broader and more pear-shaped, 
owing to the growth of the intestine. The eyes are completed; 
the iris is of a golden color. The back is now flecked with 
golden dots. They spend much of their time sticking to the 
sides of the aquarium, but it is probably not by means of their 
holders, since sections taken two days later show that these 
have disappeared. No external gills are visible; neither could I 
observe that water was being taken in. Sometimes when dis- 
turbed they would start off and spin round and round in the 
water for awhile before taking any definite course. By the rapid 
streaming of water over the body it was evident that a vigorous 
ciliary action was going on. 
On the 13th the external gills were gone, water was to be seen 
streaming through the nostrils and out through the pore on the 
left side, which alone appeared to be open. The body is pear- 
shaped. The back is black, speckled with gold ; the belly is also 
black and gold except along the middle line, where it is transparent 
enough to show the coils of intestines. The now open mouth is 
triangular, and the jaws furnished with black, minutely denticu- 
lated, homy sheaths. One specimen examined had these alone ; 
another had, in addition, two rows of black horny teeth on the 
