BATRACHIA. 



337 



United States is the JT. versicolor, and the common and only European species is the 

 IT. arborea. 



The Hylce of North America lay their eggs in the water, on some fixed hody, as an 

 aquatic plant, in smaller packets than those of the frogs, and not in strings, as do the 

 toads. The young of the S. versicolor are gray, and they undergo their metamor- 

 phoses while small. 



The TlyleUa platycephala of southern Mexico is said to deposit its eggs in the water 

 which accumulates in the axils of the leaves of certain plants of the genus Tillandsia, 

 and to undergo its metamorphosis high above the ground. The species of Noto- 

 trema and Opisthodelphys have another method of carrying their eggs. They place 

 them on their back, and in a pocket formed by the infolding of the dorsal skin. 

 This is forced upwards from a point on the coccyx, in the manner of the finger of a 

 glove, and expands so as to cover, when distended with eggs, almost the whole dorsal 

 region, see Fig. 191. In JVbto- 

 trema marsupiatum. of Peru, 

 the young leave the pouch 

 while tadpoles. In N. testu- 

 dineum and in Opisthodelphys 

 ovifera, they pass through 

 their entire metamorphosis in 

 this singular position. In the 

 latter species the branchiae of 

 the larvae are of a peculiar 

 bell-shape. 



The species of Hylidae are 

 noted for their loud and varied 

 voices. The first note of 

 spring in the United States 

 is the shrill piping of the 

 Hyla pickeritigii in the 

 swamps. If these little ani- 

 mals are imprisoned at this 

 time in a vessel, the deafening 



loudness of their voice can be appreciated. Near the same time the rattle of the 

 Acris gryllus is heard from the same localities. A similar but weaker sound can be 

 produced by violently rattling clay-stone pebbles together. Later in the season, in 

 similar localities of a generally more sandy character, the voice of the Heloecetes triseria- 

 tiis is heard. The note of this frog may, in fact, be heard all summer in swampy ground, 

 which it never leaves for the trees. It may be imitated by scraping a coarse toothed 

 comb, and at the same time lifting it from some confined space, as of a pitcher, to its 

 mouth. It is, in other words, a rattle with a rising inflection at the end, more delib- 

 erately uttered than that of Acris crepitans. In the spring, especially when it rains, 

 the country is vocal in the evening with the clear, loud, trilled rattle of the Jlyla 

 versicolor. This species also continues its vocalization at intervals through the 

 summer, mostly in the evening. The Acris and Heloecetes may be heard during the 

 day as well. In the autumn the tree-frog that is most frequently heard is Syla 

 pickeringii. Its voice is less vivacious than in the spring, and its lonely pipe in 

 dry woodlands is always associated with golden-rods and asters and falling leaves. 

 VOL. III. — 22 



Fig. Wl.— Acris gryllus. 



