136 University of Texas Bulletin 



shoulder and the seam. In the larger whorls this steep wall becomes 

 still narrower and tends to disappear. The umbilicus is narrow and 

 very deep. All the whorls show moderately deep constrictions on the 

 cast, which correspond to internal varices on the shell; about three 

 to each whorl, slightly curving backward. The body chamber is 

 unknown. The inner whorls are a little different from the outer ones, 

 being still broader with respect to their height. 



In none of our specimens is the shell preserved, so that no trace of 

 ornamentation could be observed; but in a fragment of the interior 

 - surface there is a very distinct ornamentation preserved on the mould. 

 It consists of very fine transversal lines slightly curved backward, 

 especially in the middle, similar in direction to the constrictions on the 

 whorls. These fine elevated lines are separated by flat inter-spaces 

 much broader than those lines. These striae are very near together 

 on the umbilicus, but the interstices widen considerably toward the 

 ventral part. 



The suture (pi. VI, fig. 77-80) is nearly straight, only a little bent 

 backward near the siphonal region in the external side and still more 

 in the antisiphonal region on the internal part. The septa are moder- 

 ately close without ever touching each other. All the saddles are 

 entire, high, relatively broad, rounded, slightly constricted near their 

 base. The siphonal lobe is divided into two branches by a median 

 saddle. Each of the branches is bifid, the inner point (on the siphonal 

 side) being much longer than the outer one (on the umbilical side). 

 The first and second lateral and the first auxiliary lobes are trifid, the 

 middle point being much longer than the lateral ones, while these are 

 of about equal length; although the inner one seems to be sometimes 

 slightly longer. The second auxiliary lobe is practically bifid, the 

 outer point being much longer than the inner one, but on the outer side 

 the line of the outer point bulges a little, thus indicating a tendency 

 toward becoming trifid. A simple pointed lobe is visible on the um- 

 bilical wall ; it ends in one sharp point. The first lateral lobe is much 

 narrower than the siphonal one as a whole, but broader than either 

 of the branches. The second lateral lobe is a little broader than the 

 first, the first auxiliary still a little more so than the second lateral, 

 but the second lateral and the first auxiliary one decrease steadily in 

 depth compared with the first lateral; the second auxiliary is much 



