No. 405.] DEVELOPMENT AMONG ANURA. 689 
in many ways. For the sake of completeness, a number of 
forms will be mentioned that are often referred to in connec- 
tion with those that have an unusual mode of development ; 
they are forms whose embryology has been but little, if at all, 
investigated, but whose development takes place under some- 
what unusual conditions, so that the embryology is a question 
of interest. 
The eggs of the Japanese frog, Rhacophorus schlegelii, are 
laid from the middle of April to the middle of May in excava- 
tions prepared by the female in the muddy banks of paddy- 
fields, ponds, lakes, etc., 10 to I5 cm. above the water line. 
As the eggs are laid, they are fertilized, and the gelatinous 
substance about them is aérated by a kneading motion of the 
hind legs of the female. Both adults usually escape from the 
nest by breaking a hole in the side of the bank exposed to 
the water. The frothy egg-mass hardens on the outside, and 
within it the tadpoles hatch. The substance about the eggs 
. gradually collapses, and in time flows into the water, carrying 
with it the tadpoles. The eggs are about I mm. in diameter, 
and devoid of pigment until the tadpole stage, when pigment 
begins to show in the pectoral region. The segmentation is 
Said to be unequal and holoblastic, though more nearly mero- 
blastic than in any other amphibian egg. The embryo is 
described as resembling a ganoid embryo, the head being flat 
upon the yolk, and the body wedged into the large yolk-mass. 
It is interesting to note that eggs taken from the nest in 
the mud invariably die if put into water. 
4ggs that are said also to be those of Rhacophorus have 
been found in various localities in Japan, in a frothy, gelati- 
nous substance on the leaves of trees overhanging the water. 
How the eggs are deposited is not. explained. 
Two other frogs, from different parts of the world, leave 
their spawn on trees, in nests formed of leaves stuck together. 
One of these, the West-African Chiromantis guiniensis, is found 
! For an index to the forms discussed, with summary of literature referring to 
each, see Appendix, p.714. References to reviews are given after special articles. 
* The segmentation of several other anuran eggs that contain much yolk has 
not as yet been described. 
