HIGH SCHOOL ZOOLOGY. 



B9 



skin ; tlin gills, therefore, with the red blood coursing through 

 them, stand out very conspicuously from the colourless body. 

 Instead of the four toes of Necturus, there are three on the front 

 and two on the hind limbs. The only other genus of this 

 gi'oup is the Siren, of the rice-swamps in the Southern States, 

 S. lacertina (Fig. 66) which is eel-like in shape, and lacks the 

 hind limbs. It is less aqviatic than either of the other genera, 

 and is able to live out of water for a lo.iger time. 



Fig. 66. — Siren lacertina. (After Brehm,) 



13. Of the caducibranchiate Urodeles two genera, AmpMuma 

 and Menopoma, must be regarded as nearest to the foregoing, on 

 account of the fact that in spite of the loss of the gills, one gill- 

 slit on each side (that between the third and fourth gill-arches) 

 persists, whereas in the other forms all trace of these disappears 

 in the course of development. Amphiuma (Fig. 67) is an eel- 

 like form from swamps in the Southern States ; both pairs of 

 legs are present, carrying in one species two, in the other three, 

 toes. Menopoma comes further north, being abundant in the 

 Ohio Valley where it is known as the Hellbender {M. alleghani- 

 7 



