GIRTY, THE WEWOKA FORMATION OF OKLAHOMA 145 



This species is related to C. globnJare. It appears to be a more slender 

 form (though specimens vary somewhat in this), with more distant septa 

 which show a slight lobe instead of a slight saddle on the ventral surface. 

 The sculpture of C. globulare is not known, so that additional differences 

 may be discovered when those data are determined for it. 



Horizon and locality : Wewoka formation ; Wewoka quadrangle, Coal- 

 gate quadrangle, Okla. 



Coloceras liratum var. obsoletum var. nov. 



Associated in most cases with C. liratum are specimens which show certain 

 differences, the most constant of which is perhaps the absence of lirso on the 

 umbilical zone. Correlated with this character the curvature at the sides is 

 more regular, so that the umbilical zones themselves are less well defined. The 

 incremental markings are perhaps stronger, or at least more regularly pre- 

 served. Some of the specimens are rather narrow but not all. At the same 

 time, since the sculpture on typical liratum might easily be obscured, it is 

 possible that some specimens of the latter may be included here. The siphuncle 

 of this species seems to be ventrad or at least central, while that of liratum 

 is or appears to be dorsad, but this feature is rarely shown and in the case of 

 liratum not well shown by my specimens. 



There seems to be a varietal or even a specific difference here, but my 

 material is not sufficiently good to show the degree of difference or the 

 constancy of it from C. liratum, or whether possibly the shells subsumed 

 under this title are in every case conspecific. 



Horizon and locality: Wewoka formation; Wewoka quadrangle, Coal- 

 gate quadrangle, Okla. 



Metacoceras cornutum sp. nov. 



This species is founded on a fragment which must have had a diameter of 

 70 mm. exclusive of the chamber of habitation, no portion of which is retained. 

 The whorl section is subquadrate, distinctly wider than high. The height is 

 23 mm. and the width 29 mm. The ventral surface is gently convex, more 

 nearly flat on the shell itself than on the internal mold. The sides, exclusive 

 of the prominent tubercles, are nearly flat and parallel. The lower portion 

 of the whorl is tripartite, consisting of an impressed zone about 12 mm. wide 

 and two umbilical zones, each about 8 mm. wide. The umbilical shoulder is 

 abrupt and angular, the angle being somewhat greater than a right angle. The 

 ventrolateral shoulder is also angular and furnished with large, prominent, 

 compressed nodes. They project outward and slightly upward and are flat- 

 tened on the upper surface, more convex on the lower. Those on one side 

 alternate with those on the other and in the same row they occur on about 

 every other chamber. 



The septa are about 6.5 mm. apart, measured along the median line of the 

 venter, and the sutures are rather strongly bent. There is a broad, deep 



