202 University of Texas Bulletin 



other side this species is so characteristic that even an incomplete 

 description is of a certain value, the more so as better preserved speci- 

 mens may be found at other localities. The species is extremely com- 

 mon in Runnels County, more than twenty specimens existing in Dr. 

 Beede's collection. Although our form is extremely similar externally 

 to the one found by Wrather in a much deeper horizon, it can be easily 

 distinguished from it by its more complicated suture. Our species 

 shows the following features : 



Shell semi-globular, rather involute, less curved on the flanks than 

 on the venter. Cross-section of the whorl elliptical, a little broader 

 than high, greatest width about one fourth above the umbilical border. 

 The flanks are slightly flattened ; or, better said, they are very slightly 

 curved but pass higher on in an uninterrupted curve into the strongly 

 rounded venter. The umbilicus is narrow and deep, the umbilical 

 border is rounded, the umbilical wall steep and rather broad. No or- 

 namentations could be observed on the casts or molds. 



The septa stand very near together, but do not seem to touch each 

 other. In none of the specimens could the whole suture between the 

 sipho and the umbilical border be observed, only the elements from 

 the siphonal lobe to the first lateral saddle being clearly visible. 



The siphonal lobe is very wide, a median saddle dividing it into 

 two branches. This median saddle is very high and slender, and 

 shows two branches on each side, which are separated by deep secon- 

 dary lobes and give the saddle the appearance of being extremely slen- 

 der. Each of the branches of the siphonal lobe is rather narrow, a 

 little wider at the mouth, its position is somewhat oblique with respect 

 to the line of symmetry of the siphonal saddle, and rather ramified by 

 the branches of the siphonal and the external saddle. The first lateral 

 lobe is wider and a little deeper than each branch of the siphonal one; 

 it ends in a long and sharp point and widens considerably toward the 

 mouth. The branches of the external and first lateral saddles cause 

 a number of ramifications of this lobe. The second lateral and the 

 first auxiliary lobe seem to be entirely analogous to the first lateral 

 in their form. 



The external saddle is very high, broad at the base, and fairly 

 regularly tapering toward the point. It ends in a somewhat oblique 

 phyllum and at different heights sends out on both sides alternatingly 



