518 ZOOLOGY— BATBACHLANS AND REPTILES. 



'•Thirdly, the important observation of Dumeril* established the fact 

 that the Siredons reproduced as such ; and his account of the subsequent loss 

 of larval characters by the offspring is the first of a positive character which 

 we possess on that point. 



"After this, in 1 867, + the writer recorded the various stages of meta- 

 morphosis in different structures, to be observed in reproducing individuals 

 of two species of Amblystoma, viz, — A. tigrinum and A mavorthun. These 

 embraced various Siredon characters of the dental, branchial, and dermal 

 organs, and of coloration. It was suggested that the metamorphoses observed 

 by Dumeril were those of A. mavortium, which was confirmed by an exami- 

 nation of specimens sent to the writer, by Professor Dumeril, J a year after- 

 ward. At the same time, the periods of metamorphosis of eight other species 

 of the genus were stated ; and the Mexican axolotl was regarded as an Ambly- 

 stoma, whether undergoing metamorphosis or not, owing to the irregularity 

 of its occurrence in the most nearly allied species A. mavorthun, or from its 

 Siredon stage, S. lichenoides, Baird. 



"In 1868, Professor Marsh, of Yale College, observed the metamor- 

 phosis of the A. mavortium, confirming the conclusions of previous writers. 

 Since that time, the changes have been observed by Dr. Tegetmeier and 

 others. 



" The only point remaining to be determined is whether Siredons (i. e., 

 Amblystoma mexicanum) undergo a metamorphosis or not. Among our 

 numerous specimens, I can find none that exhibit any tendency toward the 

 change. 



" I might add here that I have had for a time in a winter fernery, a 

 large New Jersey specimen of Amblystoma tigrinum a foot in length. It is 

 nocturnal in its habits, and remains during the day in its burrow. This 

 extends through the long diameter of its prison, and has three outlets, which 

 it keeps open. From one of them, as evening approaches, it projects its 

 head, and watches with attention what is transpiring in the room. 



" In the same case are specimens of the common Plethodon cinereus of 



•Bulletin Soci6t6 d'Acclimatation, 1665, ii, 348. 



t Proceedings of the Academy of Natural Sciences of Philadelphia, 166. 



I Origin of Genera, 1866, 47. 



