1 88 University of Texas Bulletin 



different from the suture of the younger specimens down to a height 

 of the whorl of ii mm., while the suture of an individual of a height 

 of the whorl of 4 mm. shows somewhat simpler elements, of the same 

 general character. 



The mature suture consists, between the sipho and the umbilical 

 border, of six lobes and five saddles ; on the umbilical border we find a 

 sixth saddle, on the umbilical wall a lobe and a saddle as well as half of 

 another lobe, the middle line of which coincides nearly with the um- 

 bilical seam. 



The siphonal lobe is extraordinarily broad and is divided into two 

 branches by a median saddle. -This median saddle is very slender 

 and high, its flanks are concave in the upper half and a deep rudi- 

 mentary lobe causes the formation of a kind of shelf above a broad 

 base, which toward both sides sends out a small but distinct rudi- 

 mentary saddle. Each of the two branches of the siphonal lobe is 

 nearly as wide as the first lateral lobe, but strongly asymmetrical, end- 

 ing in a long point. The first lateral lobe is wide and deep, of a tri- 

 angular form, if we do not consider the lateral ramifications; very 

 wide at the mouth, terminating at the lower end in a long point,- which 

 reaches a little deeper than the branches of the siphonal lobe. The 

 second lateral lobe is very similar in all its details to the first one, but 

 shallower and narrower. The first auxiliary lobe has still a general 

 similarity with the second lateral lobe but its ramifications are con- 

 siderably simpler ; this one also ends in a long point. Stil! more sim- 

 ple is the second auxiliary lobe, which shows nothing more than three 

 in part rather shallow lateral incisions or notches; the point in which 

 it ends is very short and not very sharp. The third auxiliary lobe 

 near the umbilical border is still simpler and more irregular; it shows 

 also three lateral notches and the terminal point is short and broad, 

 but the lobe itself is uncommonly wide in relation to its height. Still 

 wider is the fourth auxiliary lobe, which lies entirely on the umbilical 

 wall ; it is of an irregular form, shows on the flank nearer to the um- 

 bilical border a long point, and at the base two very shcrt points of 

 nearly equal length. Of a fifth auxiliary lobe only one half is visible; 

 it seems to be of triangular form, and the umbilical seam appears to 

 go through its median line. 



