Turritella from Buda and Georgetown Limestones 11 



Between the two middle ribs there are usually two fine 

 threads as well as striations, but in several specimens rep- 

 resenting the senile stage there is only one thread between 

 the two middle ribs and it at times becomes quite promi- 

 nent. In one specimen representing the senile stage the 

 posterior rib disappears leaving fine lines. Occasionally 

 there are found in some specimens two threads in front 

 of the anterior rib. The shape of the whorls varies some- 

 what in the different stages. The body whorl and those 

 near it are more globose than those in the older portion of 

 the spire. The base of the body whorl is rounded and is 

 ornamented with five plain, stout threads. 



Number of specimens. 45 and some fragments. 



Occurrence. Buda limestone, lower beds in the first creek 

 south of Manchaca, Texas; lower beds near contact with 

 upper beds two and one-half miles north of -Round Rock; 

 lower beds Buda, Texas; Barton Creek, Shoal Creek, Aus- 

 tin, Texas. 



Turritella felteri, n. sp. 

 Plate II, figures 7, 8 



Dimensions. Apical angle 10, suturai angle 6. 



Description. Shell small, slender, elongated, whorls, nu- 

 merous, seven or more in number, suture poorly defined, 

 sides of whorls straight. From the anterior side of the 

 whorl the ornamentation is as follows : two large tubercu- 

 lated ribs in front of which are two plain lines ; then a space 

 with fine plain threads followed by three finely tuberculated 

 ribs close together, the middle one smaller than the other 

 two ; posterior to these there is a pair of large tuberculated 

 ribs separated by a thread. The anterior of this last pair 

 of ribs is the more elevated, and the posterior is double. 



Number of specimens. 1. 



Occurrence. Buda limestone, Shoal Creek, Austin, Texas. 



