8 University of Texas Bulletin 



Our species also resembles Turritella nodosa, Roemer, but 

 varies in the size of the apical angle which is 18. 1 The 

 two upper ribs are large, rounded, and most prominent, 

 whereas the rib behind the suture is narrow but strongly 

 keeled. The fourth rib is the smallest and lies in a groove, 

 and appears as a thread in specimens not well preserved. 

 The whorls are not of the same shape. Stoliczka 2 in his 

 description of T. nodosa, Roemer, says that the spiral angle 

 is 10-12. He says that T. nodosa has five ribs of which 

 four are of equal size and the spaces between are equal. 

 Bose 3 says that Holzapfel 4 has studied T. nodosa with much 

 care and has found that the distinguishing characteristics 

 of T. nodosa are its tall, elongated figure and the existence 

 of four ribs of different size and separated by unequal 

 spaces. We have not had. access to Roemer' s original de- 

 scription. T. nodosa, Roemer, belongs to the Senonien, but 

 Stoliczka described his species from the formation that cor- 

 responds to the Cenomanian. 



Number of Specimens. 4. 



Occurrence. Lower beds of Buda limestone at Round 

 Rock, Texas. 



Turritella whitneyi, n. sp. 

 Plate I, figures 3, 4 



Dimensions. Spiral angle 3, sutural angle 9. 



Description. The shell is elongated, and because' of its 

 ornamentation resembles a Nerinea. However, this species 

 lacks the columellar plaits which are characteristic of a 

 Nerinea. Whorls are ten or more in number. Aperture 

 unknown. Whorls about one-half as high as wide. Sides 

 of whorls straight and bordered on the posterior side by a 

 broad band which is the only ornamentation of the whorls. 



iMuller, Aachen Kreide, p. 32. pi. 4, fig. 18. 



2 Stoliczka, Cret. Fauna Southern India II, p. 222, pi. 17, fig. 7; 

 pi. 19, figs. 20-21. 



3 B6se, Institute Geologico de Mexico, Boletin 25, p. 150. 

 4 Holzapfel, Aachener Kreide, I, p. 155. 



