484: ZOOLOGY. 



usually toothless. The larvae 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 Anura of Cope, i.e., 

 those with the acromial and coracoid bones divergent and 

 connected by distinct carciJage 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 

 obstetricans 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 sp^de-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 larva?,, 

 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. Our common piping 

 tree-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. 



