THE YPSILOID APPARATUS OF URODELES. 289 



the body sinks clumsily and heavily to the bottom where they 

 remain until disturbed, or until another effort is made to escape. 



Consistently with the lack of hydrostatic apparatus, lungless 

 forms show on the whole, little power to adapt themselves to 

 aquatic life. Most of them are terrestrial in habit, some of them 

 as, for example, PlctJwdon cinerens and P. glutinosus, being found 

 far from any water supply, while the arboreal Autodax furnishes 

 an extreme illustration of total abandonment of aquatic life. 

 Those species, which, like Desmognathus, live along the banks 

 of small streams, apparently never seek deep water, nor do they 

 remain long submerged in shallow water, but often are found 

 lying with the body in the water and the head (or at least the 

 nostrils) out. 1 



Lungless forms, moreover, exhibit less adaptation to aquatic 

 life in their respiratory powers, since unlike the lunged forms 

 there is practically no aquatic bucco-pharyngeal respiration. 

 When the animal is submerged, the nostrils, which have been 

 widely open during aerial bucco-pharyngeal respiration, close at 

 once and, so far as I have been able to carry my observations, 

 the nares remain closed as long as the animal is in the water. 

 In a few cases I have observed occasional feeble movements of 

 the floor of the mouth, which were undoubtedly attempts at 

 bucco-pharyngeal respiration, but even then the external nares 

 were closed and the water was both drawn in and expelled 

 through the slightly opened mouth. 



Spelerpes ruber proved to be the most aquatic of all the 

 lungless forms with which I experimented. One specimen lived 

 for weeks at the bottom of the aquarium and was never observed 

 to attempt to come to the surface except when disturbed. On 

 the other hand, specimens of Desmognathus fnsca invariably 

 escape from the water when not caged, while Plethodon glutinosus, 

 Spelerpes guttoliiieatus and Spelerpes bilineatus make frantic attempts 

 to do so, but since they do not possess the power to crawl up 

 the surface of the dry glass as Desmognathus does, their efforts 

 are unsuccessful. This aversion to aquatic life, is, however, 

 apparently not due to an actual physiological need, for speci- 

 mens of DesinognatJius fusca, Plethodon glutinosns and Spelerpes 



1 See my article now in press on the "Naso-labial Groove of Lungless Sala- 

 manders." 



