29 



fin-like membrane, and soon develops fore and hind limbs. Its trans- 

 formation to the adult form occurs when a length of about two inches 

 has been reached. (Cope, 51, 49.) 



Like the related species, this salamander swims readily by vigorous 

 strokes of its flat tail, while the limbs are held appressed to the sides. 

 They are often found floating on the water of the aquarium. When 

 disturbed they immediately plunge to the bottom and seek to hide. 

 Their food-habits are closely like those of A. tigrinum. They devour 

 with great greediness the angleworms that one offers them. The worms 

 are swallowed by a succession of gulps. One was observed to swallow 

 three inches of worm in five minutes. Prof. S. W. Garman has observed 

 that the tail is prehensile and employed to prevent the animal from fall- 

 ing. I have observed the same thing. 



This species, like A. tigrinum and A. microstomum, when under the 

 water draws this in through the nostrils and at intervals expels it by the 

 mouth. In this way they are enabled to remain for considerable periods 

 under the water away from the air. 



Ambystoma opacum, (Gravenhorst). 

 Marbled Salamander. 



Salam andra opaca, GraYeuhomt, 1807, 105,- 4S1; Salamandra fasciata, 

 Holbrook, 1842, 54, v. 71, pi. 23 ; Ambystoma opaca, Baird, 1849, 3, 283; 

 Amblystoma opacum. Cope, 1867, 1, 173 ; 51, 54 with figures ; Boulenger, 

 1882, 28, 40. 



A species with a short, stout, swollen body, short tail, and weak limbs; 

 the color dark, with light colored cross-bands. 



The greatest width of the head is about three-fourths of the distance 

 from the snout to the gular fold. The neck is distinct ; the mouth ex- 

 tends half way to the gular fold. Tongue extensively free at the sides, 

 and with the papillary folds radiating from behind. The vomero-palatine 

 teeth consist of two lateral and a median series, the interruptions occur- 

 ring just behind the choanse. 



The body has a swollen appearance. The length to the axilla is con- 

 tained in the distance to the groin two and one-third times. There are 

 eleven costal folds, and but slight indications of a dorsal groove. The 

 limbs are but moderately developed. The animal has the appearance of 

 being clumsy and weak. The tail is short and stout, its length equaling 

 only two-thirds the distance from the snout to the groin. The plantar 

 tubercle is wanting. The skin is everywhere pitted with minute pores. 



The color is a dark brown or black. Across the back and upper side 

 of the tail are a dozen light gray, or silvery white bands. These are 

 broadest on the body. They usually fork on the sides and run together. 



