150 



NEW YORK ZOOLOGICAL SOCIETY. 



COMMUX XEWT, DIEMYCTYLVS VIRlDEi,LL..\ . 



the curious transformation of the gills took place. A\'hen first 

 placed in the water their gill stalks were much aborted, appear- 

 ing as mere stumps, with little or no traces of filaments. During 

 the first week in water the animals often came to the surface for 

 air. At the end of this time the gill stalks had become longer, 

 and were well studded with short crimson filaments. The devel- 

 opment of the gills increased until the filaments were as long and 

 feathery as those of Necturus — the Mud Puppy. 



The Siren is fond of small frogs, and consumes its prey in a 

 manner that seems quite voracious for such a soft-bodied crea- 

 ture. When two individuals seize the same frog they spin in oppo- 

 site directions, soon dismembering the animal. 



Another observation relating to a transformation of the branchiae 

 of aquatic batrichians concerns the Mud Puppy (Necturus macu- 

 latus). Specimens received from cold lakes had very short gill 

 stalks, and these were provided with a very rudimentary fringe — 

 quite unlike the feathery branchiae of the majority of specimens. 

 In the comparatively warm water of an indoor aquarium, neces- 

 sitating more elaborate processes for aerating the blood, a change 



