New Species of Batracian Reptiles. 55 
length of the tail two inches eight tenths; general colour dark 
slate-green; abdomen white or yellow, sometimes mixed; 
beneath the throat mottled; tail elongated, compressed, fur- 
nished with a membranous fringe on the upper and lower 
borders. 
The extremities, or legs, which are about appearing, are 
not merely hid beneath the skin, as was asserted by Daudin, 
but exist as mere rudiments, and grow out like the stem of a 
tree. 
It has not yet been accurately ascertained how long a time 
it requires for these larve to complete their metamorphose, 
ar how frequently during the year the frogs produce their 
spawn: we know that some of the young of these animals 
pass the winéer ina larve state. About the commencement 
of April, in the vicinity of Philadelphia, they were observed 
with the posterior extremities half formed, and, a few days 
later, an immense quantity of spawn with the foetuses nearly 
ready to escape. In warmer situations indeed, the bottoms of 
the ponds were already covered with young tadpoles. 
According to.some authors, the young are hatched in fifteen 
days, and are transformed into frogs in two months* (Lacé- 
pede): according to others, two years are required for this 
metamorphose. ‘ The Jackie of Surinam remains sometimes 
for more than two years under the form of a tadpole; and 
even after it has become a perfect animal, it still preserves 
its tail for a certain time, which has given rise to the notion, 
that it is converted into a fish, and accounts for the name 
Rana paradoca. 
A similar phenomenon has been observed in the Bufo sco- 
rodasma. (Vide Dict. des Sc. Med., Art. Germ. p. 259.) 
It was by inquiries directed to this stage of the animal’s ex- 
istence, that Spallanzani, after Swammerdam, was enabled to 
detect one of the most curious facts which physiology has 
gained from natural history. The egg of a frog plunged inte 
water, swells, and, becoming transparent, permits us to see a 
blackish body, which the microscope proves to be a tadpole.” 
And Spallanzani convinced himself of the existence of tadpoles 
in the eggs laid by a female which had been entirely excluded 
ee aedentenmmentintemeas nal 
*This period varies under various circumstances, as the degree of 
heat, &c. to which the spawn is exposed. Shaw, in Zoo]. Gen., mentions 
one month, or five weekn 
