1572 The Zoologist— March, 1869 



small dark spots along llie sirles of the tail. From this stage onward 

 the variation in colour in different individuals became very marked. 

 Of the two specimens exposed to a strong light in the glass vessel, one 

 rapidly became covered with dark spots, especially on the back and 

 sides, until finally these predominated, and the grayish yellow of the 

 ground colour only remained in vertical and irregular patches, the rest 

 being a greenish black. The companion of this specimen, however, 

 although apparently equally advanced in development, retained for 

 some time nearly the original siredon colour, the only difference being 

 some irregular blotches on the sides, to which the specific name 

 lichenoides would very appropiately apply. These were the extremes 

 of colouring after the change, the other specimens showing various 

 intermediate grades, one individual having dark brown spots on a light 

 olive ground. All the altered specimens, it should be stated, apparently 

 belonged to the species Amblystoma Mavortium, as recently defined 

 by Prof. Cope, in his able Review of the Amblystomidae ;* and it is 

 an interesting fact that among the six specimens that have already 

 changed the present coloration appears to indicate two, if not three, of 

 the forms which he there regards as varieties, although previously con- 

 sidered as species by other eminent authorities. In this place should 

 perhaps be mentioned a remarkable change of colour which took place 

 in one of the siredons before any indications of metamorphosis had 

 been detected. The animal had been in the dark for several days, and 

 was then placed in a white porcelain vessel, and kept for several hours 

 in a strong light, while an attempt was made to photograph it. 

 During this time it changed from the dark siredon colour to a very 

 light yellow. The next morning the original colour had returned, but 

 a second exposure produced the same change, which was as speedily 

 reversed on returning the animal to tlie dark, although it evidently 

 suffered considerably from the treatment. Even a moderately 

 strong light appeared to be distasteful to all the siredons, and 

 they usually sought the darkest part of the space in which they were 

 confined. 



The second distinct phase in the metamorphosis, which, however, 

 commenced in every instance before the change in colour had made 

 much progress, was the absorption of the dorsal and caudal mem- 

 branes. This began on the lower margin of the tail, and soon after 

 could be detected in the dorsal region, and then farther back, the last 



* Proceedings Pliilatlelpbia Acad., xlx., p. 166, 1867. 



