Raymond : Fauna of Upper Devonian of Montana. 149 



cameras are shallow, there being seven in a length of i6 mm. The 

 sutures are nearly straight, the septa strongly convex. The siphon 

 tube is 1.5 mm. in diameter where the shell is 14 mm. in diameter 

 and has the same measurement at the smaller end of another specimen 

 where the shell is 7 mm. in diameter. The siphuncle is slightly off 

 the center of the shell, but whether dorsad or ventrad cannot be 

 determined. No specimen in the collection shows any part of a 

 living chamber that can be referred to this species. 



The specimens are replaced by hematite and pyrite and are not 

 crushed. One of the specimens sectioned shows the short siphonal 

 funnels very well as the siphuncle contained only a very soft clay 

 which was easily removed. All the other specimens sectioned were 

 entirely filled with the hematite and the siphon tube could not be 

 distinguished. 



Locality. — This species is rather common in the red fissile shale of 

 the Upper Devonian at Three Forks, Montana. 



Genus Geisonoceras Hyatt. 

 Geisonoceras normale sp. nov. 



(Plate VI, figure 7.) 



Shell small, gradually tapering, circular in section. The living 

 chamber is preserved in one specimen, and is about as long as eight 

 cameras and apparently comprises one third of the shell. None of 

 the cameras are deep, but they become more shallow on approaching 

 the living chamber. On the best specimen the three cameras nearest 

 the living chamber together occupy a length of only 3 mm., while the 

 next three occupy 5 mm. The sutures are almost straight, the septa 

 moderately convex, the siphon tube very small, and the siphonal 

 funnels very short and delicate. The position of the siphuncle seems 

 to be somewhat variable. In some specimens it is almost central, 

 while in others it is nearly half way between the center and the margin. 



This species may be distinguished from the last by its much smaller 

 size, shallower cameras, smaller and more eccentrically placed siphuncle. 



Locality. — This species is rather common in the red shale of the 

 Upper Devonian at Three Forks, Montana. 



Geisonoceras accelerans sp. nov. 



(Plate VI, figures 8, 9.) 

 This species is very similar to the last, differing from it principally 



