7-2 University of Texas Bulletin 



I cannot see any necessity for a further sub-division of the genus 

 Medlicottia in the sense that this has been limited by NoetHng. All 

 the species described are more or less intimately related to each other ; 

 even the circumstance that in some species the siphonal lobe is trifid, 

 while in others it is bifid, does not seem to be of essential importance. 



The genus Medlicottia in the restricted sense is entirely limited to 

 the Permian, while the nearly related Episageceras is found both in 

 the Permian and in the Triassic. 



Fig. 1. Medlicottia Whitney i nov. sp. Mature external suture. 



Medlicottia Whitneyi nov. sp. 

 PI. I, Fig. 41 -45a 



•' ; : 



Shall discoidal, very involute, flattened on the flanks, with a sharp 

 keel on both sides of the narrow venter and a deep median groove 

 between them. The cross-section is sagittate but truncated and hol- 

 , lowed at the ventral part and profoundly incised on the dorsal side 

 by the next smaller whorl. The whorls are deeply embracing, the um- 

 bilicus is very small, the umbilical border is slightly rounded, the 

 umbilical wall is vertical but narrow. 



On the exterior whorl we observe a very shallow, broad, spiral 

 depression at about two-thirds of the height of the flank. It does not 

 seem to run parallel to the ventral keel, but to get nearer to it on the 

 inner part of this same whorl. At the end of the last whorl the ventral 

 keels are very sharp, and even slightly elevated above the ventral 

 portion which slopes down toward the median groove ; and is separated 

 from it by a rounded edge. The flanks in this part of the whorl are 

 absolutely smooth. About half a whorl's length farther inward, the 

 uppermost part of the fllank shows a series of low rounded ribs or 

 plications, leaning strongly forward; counting from the vential 

 shoulder these ribs cover about one-fifth of the breadth of the flank; 



