GIRTY, THE WEWOKA FORMATION OF OKLAHOMA 143 



I am inclined to believe that this peculiarity of configuration is not so 

 much a specific character as that it is either generic or else of no fixed 

 value at all, but I feel that its significance is too little understood to 

 warrant establishing a new genus on the evidence in hand. 



It is with extreme rarity that shells of this group are found in a com- 

 plete condition, and all of those examined are pretty clearly imperfect at 

 one or both ends. A few give evidence of having been broken before 

 fossilization. The evidence referred to consists of the occurrence of small 

 Eoemerellas apparently in their original position of attachment upon the 

 septa, where, of course, they could not possibly have penetrated if the 

 shell had not been a fragment during the life of the brachiopod. 



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

 gate quadrangle, Okla. 



Pseudorthoceras gen. nov. 



Shells small (?), straight, gradually tapering. Siphuncle nearly central, 

 small, but considerably expanded between the septa, without, however, be- 

 coming nummuloidal. Septa simple. Funnels apparently very short and 

 thick. Chambers partly occupied by secondary deposits which accumulated, 

 not about the funnels and siphuncle, but about the walls. In the type species, 

 the deposits fill about half of each chamber, thinnest toward the aperture and 

 thickest toward the apex, and diminishing irregularly so that the outline is 

 shaped like an incomplete letter S. The deposit appears to be more or less 

 vesicular, perhaps as the result of weathering. Shells which are not broken 

 at the apex do not taper to a point, but are obliquely truncated. 



This type is rather clearly not a representative of true Orthoceras, nor 

 have I been able to find a genus with which it can be assembled. Indeed, 

 it is not certain that it can be included among the Orthoceratidae, though 

 it is for the present referred to that family. The most diagnostic feat- 

 ures are probably the enlarged siphuncle and more especially the second- 

 ary deposits accumulated not axially, but circumferentially. In this item 

 lies the main difference from Orthoceras, for in that genus, and indeed in 

 that family, the secondary deposits are rather sparingly developed and 

 they are accumulated about the funnels, not about the outer wall. 



Type species, Pseudorthoceras knoxense McChesney. 



Pseudorthoceras seminolense sp. nov. 



Three specimens in the collection appear to belong to Pseudorthoceras by 

 reason of their central siphuncle and chambers partly filled by secondary 

 deposits and at the same time to differ from P. knoxense in being very much 

 larger. These large specimens have about 3.5 chambers to a diameter and so 

 do not differ essentially from the smaller species. One of the specimens is 



