92 EDUARD UHLENHUTH. 



greatest value to raise the Typhlomolge, in order to study closely 

 their mode of propagation, development and to subject these 

 animals to certain experiments indicated by our present technic 

 in the study of the metamorphosis of other salamanders. 



In connection with the metamorphosis of Typhlomolge it may 

 be pointed out that Miss Emmerson has made a statement which 

 is so important that it arouses curiosity as to why it has attracted 

 so little attention. Miss Emmerson searching for the organs of 

 internal secretion of Typhlomolge found that the animal possesses 

 a thymus gland, but she could not find a thyroid gland. If the 

 lack of a thyroid gland could be confirmed and we are prepar- 

 ing some of our specimens for examination with that end in 

 view Miss Emmerson's discovery will explain why the Typhlo- 

 molge cannot metamorphose at present, since Allen has demon- 

 strated that larvae of frogs and toads whose thyroids were ex- 

 tirpated did not metamorphose, though the controls with intact 

 thyroids all metamorphosed. Do the Proteidas (Proteus) possess 

 thyroids, is the lack of the gland common to all of them? And 

 what are the reasons for the atrophy of the gland? These are 

 problems which call urgently for investigation. 



From the facts mentioned above it is certain that the Typhlo- 

 molge inhabit the subterranean waters which constitute the 

 Purgatory Creek System and a subterranean water channel which 

 supplies the San Marcos Artesian Well. These two systems are 

 located north and south respectively from the Balcones scarp 

 line. On account of the faulting, though both the Purgatory 

 Creek Caves and the Artesian Well Cave are located in the same 

 geological formation, the latter cave occupies a position several 

 hundred feet deeper than the Purgatory Creek Cave; this is 

 indicated in the diagram, Fig. 12. The water in both systems is 

 of different origin, as may be seen from this diagram. The 

 water of the Artesian Well is the so-called "sweet water," which 

 on the plateau, i.e., in the region of the Purgatory Creek System, 

 is carried in beds below those in which the caves of the Purga- 

 tory Creek System are located. The " sweet water " is caught by 

 the basement beds of the Cretaceous, the Travis Peak and Glen 

 Rose formation, where they outcrop on the plateau, and is carried 



