290 INEZ L. WHIFFLE. 



guttolineatus suffer no physiological inconvenience when com- 

 pelled to remain under water as in the experiment described 

 above in which they were confined in wire cages immersed in 

 running water for a week or more without access to air. They 

 invariably, however, as soon as released, swam to the surface of 

 the water and tried to escape, thus showing a strong instinct to 

 seek terrestrial conditions even though their physiological needs 

 were satisfied. It cannot, therefore, be argued that the aversion 

 to aquatic life is due to lack of lungs and correlated ypsiloid 

 apparatus but rather that the long continued terrestrial habit has 

 resulted in the loss of these structures. An aquatic lungless 

 form like Spclerpes ruber must then be regarded as having sec- 

 ondarily reacquired its aquatic habits. 



Salamandrina, a lungless form which possesses an ypsiloid 

 apparatus, is an interesting exception but by no means an em- 

 barrassing one, since it belongs to a wholly different group of 

 salamanders and thus represents a case of analogical resemblance. 

 It might be expected a priori to show less divergence in structure 

 from the lunged salamanders than do the members of the families 

 Plethodontid(Z and Desmognathidce, since its departure from the 

 habits of the rest of its own family, the Pleurodelidce, is presum- 

 ably comparatively recent. Thus we find that it still possesses 

 arytenoid cartilages and rudiments of lungs. Similarly the ypsi- 

 loid apparatus persists, though Wiedersheim ('75) called attention 

 to the fact that the cartilage is less strongly developed than in 

 the case of Triton in which it usually undergoes more or less 

 calcification. There are additional evidences in the condition of 

 the muscles of the region (already described) that slight degen- 

 eration of the apparatus has taken place. 



Of course a secondary adaptation to some other function might 

 tend to preserve the apparatus, but as I have not yet had the op- 

 portunity to observe the living Salamandrina I can make no 

 statement as to the probabilities of such secondary adaptation. 



E. The Hydrostatic Functions of Perennibranches 

 and Derotremes. 



The following table expresses briefly the conditions of lower 

 Urodeles with reference to the possession of lungs and ypsiloid 



