174 BATRACHIA. 
Cuass F. BATRACHIA. (THE BATRACHIANS.) 
Cold-blooded vertebrates, intermediate between the fishes and the 
reptiles. They differ from the fishes chiefly in the absence of rayed 
fins, the limbs being usually developed and functional with the 
skeletal elements of the limbs of reptiles, and in the reduction or 
absence of the various bones of the branchial, opercular and sus- 
pensory systems. 
The Batrachians undergo a more or less complete metamorphosis ; 
the young (“tadpoles ”) being fish-like and more or less aquatic, 
breathing by means of external gills. These differ from the gills 
of fishes in standing on fleshy processes of the branchial bones and 
not on the bones themselves. In the tadpole, the tail is provided 
with a more or less distinct fin-like membrane, which usually dis- 
appears with age. Later in life, lungs are developed, and in most 
cases the gills disappear. Skin mostly naked and moist, used to 
some extent as an organ of respiration. Heart with two auricles 
and a single ventricle. 
Reproduction by means of eggs which are of comparatively 
small size, without hard shell. These are deposited in water or in 
damp places. In one salamander the young are born alive. Pro- 
fessor Cope recognizes nine orders of Batrachians, four of these 
being extinct. (@drpaxos, frog.) 
Orders of Batrachia. 
u. Body lengthened, with a distinct tail throughout life; hind limbs, if present, 
not especially enlarged. 
6, External gills and gill-clefts persistent throughout life, the gills 3 on 
each side; no eyelids; vertebre amphiccelian; maxillary small or 
wanting. 
ce. Body eel-shaped, without hind le teeth on vomer; floor of mouth 
rough; jaws with horny sheath.. . . Tracuystomata, XXIV. 
cc. Body salamander-shaped, the hind limbs present; jaws with teeth. 
PROTEIDA, XXV. 
6b. External gills normally disappearing in adult life; limbs 4 (or want- 
ing, present in all our species); pu with teeth; maxillaries and 
palatines present. . . . - » « « Uropeua, XXVI. 
aa. Body short, depressed; tail disappearing with age; limbs 4, the posterior 
muchenlarged. . - - 2. ©. . . + Speman, XX VIL 
Oana 
