1 6 INEZ L. WHIFFLE. 



as to flow over the external nares, these immediately close, while 

 bucco-pharyngeal respiration at once ceases and the floor of the 

 mouth is forcibly indrawn, causing, often, the expulsion of tiny 

 bubbles of air through the nares which open sufficiently to per- 

 mit their escape. All entrance of water into the nasal passages 

 is, by this prompt closing of the nares, effectually prevented. 

 There is, moreover, an independent control of the two nares, 

 since, when the animal is so manipulated that only one naris is 

 covered with water, this one alone is closed, while, through the 

 other, aerial respiration continues. Especially noticeable is the 

 almost immediate resumption of aerial respiration, when, after the 

 interruption caused by immersion, the snout is thrust out of water 

 sufficiently to bring the nares above its surface. Even if only a 

 single naris gains access to the air, this alone opens and the 

 bucco-pharyngeal movements begin again. 



All of the forms which I have experimented with, however 

 (/. e., various species of Plctlwdon, Desinognatlins and Spc/erpcs'], 

 show, with the exception of Spelerpes rubcr, a strong aversion to 

 deep water. When placed in water of too great depth to allow 

 them to raise the tip of the snout above the surface while they 

 are standing upon the bottom, they invariably make frantic efforts 

 to escape. They swim rapidly to the top and hold themselves 

 there by active swimming motions. When unable to sustain 

 themselves longer at the surface, since, in the absence of lungs, 

 they have no hydrostatic powers, they fall to the bottom where 

 they remain for a longer or shorter period of rest. During all 

 these manoeuvres the tightly closed condition of the nares and 

 the elevated position of the floor of the mouth are maintained. 

 Moreover, from my observation of Dcsnwgnatlms fusca and 

 Spelerpes bilineatus in their natural environment, I am convinced 

 that these species, at least, never voluntarily seek deep water ; 

 and when driven into deeper parts of the stream, they soon make 

 their way under cover of fallen leaves and debris to a region 

 where the depth is not too great to allow the snout to be thrust 

 out of water. Under this condition they are perfectly at ease 

 and will remain with the body in water for a long time if only 

 the nare*s have access to the air so that bucco-pharyngeal respi- 

 ration may continue. 



