ZOOLOGY. 439 
loupe, a voleanic island, the soil of which is composed of tufa, 
pozzuolana and similar material, are so peculiar and so very unfa- 
vorable for the maintenance of tadpole life, which is essentially 
piscine, that M. Baray was led to expect the existence of some 
peculiarities of development. The ova were easily procured, as 
they were everywhere present under moist leaves. No tadpoles 
could be discovered, but many of the frogs were of an extraordi- 
narily minute size. . The eggs were spherical, with a diameter of 
from three to four millimetres, and were each provided with a 
small spheroidal expansion resembling a hernia of the gelatinous 
mass through a pore in the envelope. In the centre of the sphere 
the embryo was visible, lying on a vitelline mass of a dirty 
white color, and having a thin body, a large head and four 
styliform members with a recurved tail. When the egg was 
touched the embryo moved rapidly and changed its position. A 
day later the embryo was perfect, with a tail as long as the body, 
translucent and like that of a tadpole. The limbs immediately 
formed, and at the expiration of a few days little frogs of a dark 
grayish brown color, and without a vestige of a tail, escaped from 
the egg. M. Baray’s observations have established the following 
facts: —1. That this Hylodes Martinicensis commences life by a 
rotatory movement of the future embryo; 2. The fully formed 
embryo performs the rotatory movements more rapidly, but ina 
horizontal plane; 3. The branchiz make their appearance, and 
again vanish sometime afterwards; 4. The larva in the ovum is 
provided with a tail and limbs; 5. The tail of the larva not only 
facilitates the movements of the imprisoned animal, but also aids 
respiration by the numerous and minute vessels which ramify in 
this highly developed appendage; 6. The animal issues from the 
egg in the form which it preserves throughout life. As M. Garnier 
observes, these observations seem to constitute a starting-point 
for a special investigation of great importance, and have a close 
relation to the question of the adaptability of species to surround- 
ing conditions. It may be asked in this case whether the frog has 
been created with special modifications adapting it to live in an 
island destitute of marshes, or has it in course of time acquired a 
new mode of development enabling it to survive under the excep- 
tional conditions under which it has been placed. — The Academy. 
Tue PALEONTOLOGICAL History OF TRILOBITES, ETC., AS OP- 
POSED BY BARRANDE, TO THE EVOLUTION Tueory. — During the 
