484 ZOOLOGY. 
usually toothless. The larve are called tadpoles, and repre- 
sent the adult form of the Perennibranchiates. The exter- 
nal gills are in the adult replaced by shorter internal ones. 
Among the lower frogs or arciferous Anwra of Cope, i.¢., 
those with the acromial and coracoid bones divergent and 
connected by distinct cartilage plates, are certain forms, 
as Alytes, Pelobates, and Pelodytes, whose breeding habits 
are peculiar and interesting. The eggs of Pelodytes are 
deposited in small clusters in the water, those of Pelo- 
bates in a thick loop. The male of the European Alytes 
vbstetricans winds a string of eggs which it takes from 
the female, and goes into the water, where it remains 
until the young (which have no gills) are hatched. The 
American Scaphiopus, or spade-footed toad, is not known to 
have this obstetrical habit. This singular toad appears sud- 
denly and in great numbers. It remains but a day or 
two in the water, where it lays its eggs in bunches from 
one to three inches in diameter. The tadpoles hatch 
in about six days after the eggs are laid; their growth is 
rapid, the young toads leaving the water in two or three 
weeks. The croaking of this toad is harsh, peculiar, and 
need not be confounded with that of any other species. 
(Putnam.) As the spcde-footed toads are rarely seen, it is 
possible that they burrow in the soil, like the European 
Alytes. Another peculiarity in the reproductive habits of 
Alytes, Pelobates, Cultripes, and Pelodytes is that they 
spawn at two seasons instead of one, and that their larve, 
like Pseudes (Fig. 437), attain a greater size than those of 
other frogs before completing their metamorphosis. (Cope.) 
Among the tree-toads, Polypedates of tropical Western 
Africa, contrary to the usual habits of frogs, deposits its eggs 
in a mass of jelly attached to the leaves of trees which bor- 
der the shore overhanging a pond. On the arrival of the 
rainy season, the eggs become washed into the pond below, 
where the male frog fertilizes them. Ourcommon piping 
étree-toad (Hyla Pickeringii Le Conte), about the middle of 
April, in the neighborhood of Boston, attaches her eggs 
simply to aquatic plants. The young are hatched in about 
twelve days. 
