OBSERVATIONS ON TYPHLOMOLGE RATHBUNI. 



79 



face altitude of the water about 584 feet. Mr. Johnson claims 

 that the water is flowing. There is no doubt that Johnson's Well 

 communicates with the subterranean Purgatory Creek. As in 

 the case of the San Marcos Artesian Well, the water in this com- 

 pletely water filled cave must have been under a pressure suffi- 

 ciently high to lift it to 3 feet in the well. It again is evident that 

 the Typhlomolge prefer to live in water under high pressure and 

 in caves which are filled entirely with water. The water of John- 

 son's Well has the same temperature as that of the San Marcos 

 Artesian Well and also has the same taste. Besides the Typhlo- 

 molge, Frank Johnson's Well contains also the Palcemonetes an- 

 troruin and the Cirolanides texensis. 



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FIG. 4. Purgatory Creek Valley and Frank Johnson's Well. Diagrammatic 

 section reconstructed from several cross sections. The figures indicate alti- 

 tude above sea level in feet. 



Thus, though the water of the Frank Johnson Well represents 

 the subterranean Purgatory Creek, it shows great similarity to the 

 water of the San Marcos Artesian Well. Particularly the pres- 

 ence in Purgatory Creek of 3 species typical of the artesian well 

 would suggest that in some way the Purgatory Creek water is in 

 communication with the so-called sweet water horizon near the 

 San Marcos Artesian Well. 



In Frank Johnson's Well the Typhlomolge were seen to pass 

 through the slit from the cave into the well. During my stay in 

 San Marcos, the water in the well was too high to catch the sala- 

 manders directly and for this reason traps were submerged in the 

 well. These were ordinary minnow traps. In the beginning they 



