196 University of Texas Bulletin 



branch Esi, lying on the venter, and the flank, is considerably higher 

 and more complicate than the one nearer the umbilicus, Esj. On its 

 flank near the ventral furrow Esi is notched by five rudimentary lobes 

 directed obliquely downward; on the flank nearer to the umbilicus it 

 shows five rudimentary lobes which are much deeper and in a position 

 nearly perpendicular to the spiral line. The lowest shows a slight swell- 

 ing in the middle of its bottom ; the bottom of the rest is rounded. At 

 , the end of Esi two lateral and very shallow notches produce a button- 

 like point. We count, therefore, altogether, ten, or if we count the two 

 notches, twelve rudimentary lobes on a specimen which has about the 

 same size as the one of Medlicottia n. sp. II, the suture of which will 

 be described later on. The rudimentary saddles lying between the 

 rudimentary lobes on the flank near the ventral furrow are very short 

 and rounded ; those on the opposite flank are very long, the longest one 

 being the lowest which forms the limit of the adventive lobe "A" ; the 

 next higher one is much shorter and the following decrease rapidly in 

 length, this flank of Esi taking thus the form of one side of a pyramid 

 tapering upward. The adventive lobe "A" is much larger than the 

 rudimentary ones, it is divided by a slender and rather long secondary 

 saddle in two parts, the lower one of which is deeper than the higher 

 one; the lobe is much narrower at its mouth than at the bottom. The 

 following branch, Es2, of the external saddle is simply tongue-shaped, 

 but a slight lateral swelling on each side indicates an inclination to- 

 ward a trilobate form; this saddle is high, slender and slightly con- 

 stricted near the base. It is much shorter and narrower than the first 

 lateral saddle and leans strongly over toward the first lateral lobe. 

 The first lateral saddle is much larger than Es2, shows a slight lateral 

 swelling on each side without becoming trilobate ; it is rather tongue- 

 shaped, high, slender and well constricted near its base. The second 

 lateral. saddle is very similar to the first-one, but a little higher; in the 

 same way, the first auxiliary saddle is only a little shorter than the 

 second lateral one. These two also show the lateral swelling on both 

 sides, but the constriction lies a little higher above the base than in the 

 first lateral saddle. The next three auxiliary saddles which can be 

 seen in one of our specimens are very similar to the lateral ones, only 

 less high. Their height decreases slowly in the direction toward the 



