6o University of Texas Bulletin 



Uddenites so far has been found only in the Wolfcamp formation, 

 the very lowest part of our Permo-Carboniferous. 



Uddenites S chuck erti nov. sp. 

 PI. I. Fig. 9-23 



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

 gion, the latter with a median furrow in the adult whorls, and slightly 

 rounded in the juvenile ones. The furrow is slightly narrower than 

 each of the flattened parts on its side ; flanks and ventral part form a 

 right angle but the ventral border is somewhat rounded. The cross- 

 section of the adult whorl is nearly rectangular, with the exception of 

 that part which embraces the next smaller whorl, and not taking into 

 account the furrow on the ventral part. The cross-section of the 

 smaller whorls is rectangular, but the ventral part is slightly curved. 

 The umbilicus is very narrow, its border is rounded, its- wall is nar- 

 row but steep. No ornamentation is visible on the cast. The body 

 chamber is unknown. 



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

 The suture forms a nearly straight line. The final stage of the suture 

 consists of a siphonal and eight lateral and auxiliary lobes, the last one 

 on the umbilical shoulder, and a ninth on the umbilical wall. These are 

 separated by eight saddles on the ventral part and flank, and two or 

 more on the umbilical wall. 



The siphonal lobe is deep and trifid, the middle part most promi- 

 nent but apparently not closed. The lateral points are small and 

 sharp. The lobe is much narrower at its top than near the base; it 

 occupies about the width of the furrow on the ventral part. The first 

 lateral lobe is extremely broad ; it occupies part of the ventral region, 

 the ventral shoulder and part of the flank; it is subdivided into four 

 branches by three secondary saddles, the outer one of which is large 

 and bent over toward the umbilicus. The branch between this sec- 

 ondary saddle and the first lateral one is not nearly as deep as 

 the siphonal lobe, but deeper than any of the lateral lobes. It is 

 curved with the convexity toward the umbilicus. The other two sec- 

 ondary saddles with their three lobes form a saw-tooth-like line, the 

 outer secondary saddle being a little higher than the other one. The 

 second lateral lobe is symmetrical, not as deep as the first one, some- 



