The Zoologist — March, 1869. 



1569 



Observationft on the Melamorphosis of Slredon into Ainblystoma. 



By. O. Q. Marsh.* 



lig. 1. Undeveloped larva of Amblystoma Mavortium of Baird, hitherto known as 

 Siredon lichenoides of Baird (half natural size). 



Fig. 1 a. View from below, showing the arrangement of the maxillary and palatine 

 series of larval teeth and inner nostrils of the same. 



Kg. 2. Amblystoma Mavortium developed from Siredon lichenoides : metamorphosis 

 apparently completed (half natural size). 



Fig. 2 a. Maxillary and palatine teeth of the same after metamorphosis. 



While on a geological excursion to the Rocky Mountains, during 

 the past summer vacation, the writer obtained at Lake Como, in 

 Wyoming Territory, a number of specimens of Siredon lichenoides, 

 one of the most interesting forms of the Urodela, or tailed Batrachians, 

 and one hitherto but little studied. This lake is a small shallow sheet 

 of water, distinctly brackish, or " alkaline," apparently from the salts 

 of soda. It lies near the Union Pacific Railroad, about 640 miles 

 west of Omaha, and at an elevation of about 7000 feet above the sea. 

 The surrounding region is an arid desert, with little or no vegetation, 

 except cactus and wild sage. 



The siredons obtained at this locality, where the species, known as 

 the " fish with legs," is quite abundant, showed at first no differences, 



* Reprinted from the 'American Journal of Science and Arts,' and communicated 

 by the Author. 



SECOND SERIES — VOL. IV. M 



