478 ZOOLOOY. 



observed at the Yukon Purer in lat. 60° X., but the climate 

 there is milder than that of Labrador. The common toad 

 and a salamander {Pletliodon glutinosa Baird ?) extend to 

 Southern Labrador. 



Kearly 700 species of existing Batrachians are known, 101 

 of which are North American, and about 100 fossil forms 

 have been described. 



There are five orders of Batrachians, Professor Cope's 

 classification being adopted in tliis work. Those Batrachians 

 with persistent gills are sometimes called PerennibrancMates. 



Order 1. Trachystoynata. — The sirens have a long eel-like 

 body, with persistent gills ; there is no pelvis or hind limbs, 

 and the weak, small fore legs are four or three-toed. The 

 great siren. Siren lacertina Linn., is sometimes a metre in 

 length, and has four toes in the fore leg ; it lives in swamps 

 and bayous from Xorth Carolina and Southern Illinois to 

 the G-ulf of Mexico. A small siren with three toes and 

 small gills is Pseudohranclms striatus Le Conte. It occuis 

 in Georgia. 



Order 2. Profeida. — This group is represented by the 

 Froteus of Austrian caves and the mud-puppy {Xedurus) 

 •of the United States. These Batracliians have bushy gills, 

 -«'ith gill-openings and well-developed teeth. In Proteus, 

 T\'hich is blind, tliere are three toes in the fore feet and two 

 in the hinder pair. In the mud-puppy, Xecfurus (formerly 

 Menobranchus) lateralis Baird, each foot is four-toed. The 

 head and body are broad and flat, brown with darker spots. 

 It lias small eyes and is about half a metre (from 8 inches to 

 2 feet) in length. It inhabits the Mississippi Valley, extend- 

 ing eastward into the lakes of Central Xew York. The 

 Proteus as well a^ the mud-puppy lay eggs. 



Order 3. UrodeJa. — The tailed Batrachians or Salaman- 

 ders rarely have persistent gills, those organs being larval or 

 transitory ; the body is still long and fish-like, the tail some- 

 times with a caudal fin-like expansion as in the newts, but is 

 usually rounded, and the four legs are ahvays present. With 

 onlv one or two viviparous exeeprioiis, most of them ]aveir2:s 

 in the water. The eggs of Triton are laid singly on sub- 

 merged leaves ; those of Diemyctylus viridescens are laid 



