HABITS OF CRYPTOBRANCHUS ALLEGHEN1ENSIS. I I 



in shallow water the posterior end often remains under a rock. 

 Fig. 3 shows an early stage of this movement. The air taken 

 in through the nares at the instant the tip of the snout reaches 

 the surface is probably immediately afterwards mixed with re- 

 spired air expelled from the lungs ; then the greater part of the 

 mixed air is forced back into the lungs by a swallowing move- 

 ment. The surplus air escapes through the mouth or gill slits 

 as the animal sinks to the bottom ; but enough air is forced into 

 the lungs to elevate this portion of the body, giving the back an 

 arched appearance (see Fig. 4). A little later, more of this air 

 is expelled in order to enable the animal to resume its normal 

 resting position (Fig. 2), and to prepare it for another inspiration. 



According to Whipple ('06), the ypsiloid apparatus (see also 

 Smith, '06 *) of many Urodeles subserves a hydrostatic function 

 in changing the angle of inclination of the body in a vertical 

 plane by pressing upon the posterior part of the expanded lungs 

 and forcing the air forward. It is suggested that this may be 

 the case with Cryptobranchus. But the animal makes active pad- 

 dling movements with its forelimbs in rising to the surface for 

 air ; moreover when the lungs of a freshly killed specimen are 

 inflated to the limit by means of a blow-pipe, their slender tips 

 do not reach to the ypsiloid apparatus. Hence in the case of 

 Cryptobranchus it seems impossible that the apparatus should 

 have a hydrostatic function, excepting the slight effect produced 

 by pressing the abdominal viscera forward. 



Specimens in swiftly flowing water in cool weather rarely come 

 to the surface to breathe. I have watched specimens that have 

 remained motionless on the bottom for hours. On one occasion 

 a dozen hellbenders in a covered creek aquarium built of wire 

 netting to allow a constant current of water, were submerged by 

 high water for two days without apparent injury. In these cases 

 cutaneous respiration is probably sufficient ; this may be aided 

 by pharyngeal respiration, but in specimens confined in aquaria, 

 having access to air, I have been unable to detect any current of 

 water flowing in at the mouth and out at the gills, such as occurs 

 occasionally in a resting Nectaries. According to Gage ('91) the 

 oral epithelium of Cryptobranchus is stratified and non-ciliated, 

 as is usually the case with Amphibia whose respiration is mostly 



