56 University of Texas Bulletin 



Shell discoidal, involute, with flat flanks and flattened ventral re- 

 gion, which in the inner whorls is somewhat rounded, while later on it 

 develops a deep furrow somewhat narrower than the lateral flattened 

 and elevated portions of the ventral region. The cross-section of the 

 adult whorl is nearly rectangular if we do not consider the furrow on 

 the ventral region ; the small whorls have a similar cross-section only 

 with slightly curved flanks and ventral region, so that there the cross- 

 section is rounded subrectangular. 



The inner whorls are absolutely smooth and very evolute; where 

 the Pronorites suture is visible the flanks show fairly strong trans- 

 versal ribs slightly curved backward, with the convexity toward the 

 front, beginning at the umbilicus and disappearing before they reach 

 the ventral shoulder. (PI. I, fig. 32.) They are separated by shallow 

 interstices with rounded bottom, nearly twice as wide as the ribs. At 

 the stage where the furrow begins to develop, the umbilical border 

 shows very fine radial lines of growth, slightly bent backward; the 

 rest of the cast does not show any ornamentation. 



The septa are very near together but without touching each other in 

 the largest whorl, while on the inner whorls they are farther separated. 

 The suture is nearly straight. On those inner whorls which have a 

 rounded although flattish ventral region, the sviture corresponds to 

 that of the typical Pronorites. There the siphonal lobe appears to 

 be divided into three dififerent parts, by the appearance of two second- 

 ary saddles on the sides; the middle part is open below, on each side 

 is a small secondary saddle, and a pointed secondary lobe. The 

 siphonal lobe is deep and much narrower at the upper end than below 

 the middle, at the height of the secondary lobes. The first lateral 

 lobe is very broad and divided into two branches by a small secondary 

 saddle. Both branches, as well as the secondary saddle, are rounded. 

 The second lateral lobe is about half as broad as the first one, rounded 

 at the bottom and much narrower at the upper part than below. The 

 first and second auxiliary lobes are much smaller and less deep than the 

 two lateral ones. The saddles are all entire and rounded at the top. 

 The external saddle is not very high and bends slightly toward the 

 sipho; the first lateral saddle is higher than the external, and con- 

 stricted above the base; the second lateral saddle is similar to the 

 first, but a little lower; the first auxiliary saddle is much lower than 



