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U.S. NATIONAL MUSEUM BULLETIN 2 59 



of these large springs exit thi'ough the Edwards limestone, much of 

 their water may come from aquifers developed in the Trinity forma- 

 tion. The Trinity group contains the cavernous Glen Rose limestone 

 which crops out west of the Balcones fault zone and contains a number 

 of caves in Bandera, Kendall, Comal, and Bexar Counties. Origin 

 in Glen Rose limestone of some of the ground water which ultimately 

 resurges along the Balcones fault zone would imply several rather 

 extensive subterranean drainage systems in this part of Texas, As 



MEXICO 



GULF OF 

 MEXICO 



Figure 33. — Distribution of species of Stygonedes in central Texas. [The flagellatus group: 

 A S. dejedus; A S. flagellatus; 9 S. longipes; * S. pecki. The hadenoecus group: S. 

 hadenoecus. The tenuis group: + S. halconis; X S. bifurcatus; Q S. reddelli; O S. rus- 

 selli; n Stygonedes species. Two symbols in a circle indicate two species from same 

 locality.] 



Reddell (1964b) pointed out, how^ever, the relationship between the 

 hydrologic systems and the development of caves in this region, 

 especially in the vicinity of Comal County, is still poorly known. The 

 occurrence of numerous and extensive faults further complicates the 

 picture. 



It is, then, perhaps significant that one of the four rare species of 

 the flagellatus group, i.e., S. pecki, is known only from two specimens 

 taken from the cave-like exit of Comal Springs in New Braunfels, 

 Tex. According to Reddell (1964b), this spring is the largest in the 

 southwest and produces 210 million gallons of water per day. Col- 

 lecting in caves west of New Braunfels, in areas which theoretically 



