Embryology. 263 
THE Curnca-Bue IN Iowa.—A bulletin of the Iowa Agricultu- 
ral College, by Professor Osborn, entitled The Chinch-Bug in Iowa, 
as just been issued. It includes a summary of the habits of the 
species and a discussion of some experiments in controlling this 
pest. 
EMBRYOLOGY. 
THE “ VENTRAL Suckers” or “Suckine Disks” OF THE 
TADPOLES OF DIFFERENT GENERA OF Froes AND Toaps.!— 
Thiele in this very interesting paper, shows that the singular 
sucker-like organs found behind the mouth and under side of the 
head in the tadpoles or larve of frogs and toads differ widely in 
form in different genera. They are clearly for the purpose of 
enabling the young larve to attach themselves to various fixed bodies 
in the water, such as weeds, the gelatinous egg-strings and masses 
from which they have been hatched, ete. They are thus afforded sup- 
port and prevented from sinking into the ooze to smother, and their 
enemies thus also doubtless find them a less ready prey. These 
disks are also shown by Thiele not to be of the nature of suctorial 
the sessile “suckers ”of larval toads and frogs. But the present 
writer cannot see how it is possible to homologize the sucking disk 
of larval gar pikes with the adhesive organs in larval Batrachians, 
use in the former the disk is in front of the mouth and in the 
latter it is usually quite behind the mouth, only in one case (Hyla) 
are the suckers found near the angle of the mouth, The larva of 
organ of the gar-pike’s larva and that of young toads and frogs, 
though it is probable that these organs in the latter are rai? 
£ Ftd Ha in pperat der Batrachierlarven, von Johannes Thiele. Zeitsch. 
5s. zool, xliv. pp., 67-79, pl. x. 1887. 
