TiJE Zoologist — March, 18G9. I575 



float for some time at an angle of about 45®, with the external nostrils 

 above the surface. Frequent efforts to leave the water soon followed, 

 and an opportunity of so doing was in most instances speedily improved, 

 and the change then seemed to progress more rapidly. One or two 

 specimens, however, showed for some time, especially in cool weather, 

 much less inclination to desert their native element, apparently 

 suffermg little or no inconvenience from remaining under water, if 

 allowed to come to the surface about once in five minutes. The 

 pugnacious propensities of the siredons, which at first led to occasional 

 assaults on one another, appeared to diminish as the change pro- 

 gressed, and the more sluggish nature of salamanders at last pre- 

 dominated ; but the altered forms at times showed no little 

 celerity of movement, and when irritated, especially when held by 

 the tail, would often turn and snap at the hand with a rapidity 

 that would have done uo discredit to a reptile of much higher 

 organization. 



The effect on the metamorphosis of a variation in light and tem- 

 perature has already been alluded to. During a succession of very 

 warm days, about the 1st of September, the change progressed with 

 great rapidity, but it apparently ceased, or made very slight progress, 

 in the cool week that followed. While, moreover, the two specimens 

 most favoured in regard to light and warmth passed apparently 

 through the entire transformation in about twenty days, those which 

 commenced at the same time, but were less favorably situated, required 

 at least twice that time for its completion. The only living specimen 

 still remaining unchanged has twice shown slight indications of an 

 approaching metamorphosis, but with the exception of some spots, 

 these have apparently soon disappeared after a transfer to a dark 

 and cooler place. 



Inasmuch as this species of Amblystoma appears to have never 

 before been studied from living specimens, and especiallv as its 

 larva (hitherto known as Siredon lichenoides) has but ieiy rarely 

 been met with, it may be well to mention some of the more important 

 characters noticed in the individuals just described, in addition to 

 those given in the original description of the two forms, when the 

 connection between them was unknown. It should, perhaps, be first 

 stated that, after the observations here recorded, it becomes at once 

 evident, on examining Prof. Baird's excellent description and figures 

 of Siredon lichenoides,* that the specimen on which the species was 

 * Stanbury's Exped. to the Great Salt Lake, p. 336, 1855. 



