Raymond: Fauna of Upper Devonian of Montana. 155 



to determine what is the cause of this reversion of the normal suture. 

 It is very possible that material showing the ontogeny would throw 

 some light on this perplexing form. 



Locality. — A very rare shell in the red shale at Three Forks, 

 Montana. 



Tornoceras douglassi sp. nov. 

 (Plate VIII, figures 9-14.) 



All the goniatites found in the white blocky shale, and many of 

 those from the red shale belong to the genus Tornoceras. The speci- 

 mens from the white shale are much larger 

 than thos^ from the red shale, but most of the 

 shells in the red shale are dwarfed, so that, as 

 there are no other differences between the 

 shells from the two localities, they are prob- 

 ably the same species. One of the shells from y\g. 6. Tornoceras 

 the red shales is chosen as the holotype, to douglassi Raymond, 

 avoid any confusion in case it should at any Outline drawings of the 

 time be found that there are really two species ^^P^ ^° '^'°''' '"''"■^^- 



, , Natural size. 



involved. 



Description. — Shell discoidal, involute, with a small umbilicus 

 throughout life. In the best specimen from the red shales the portion 

 of the living chamber preserved occupies about half a volution, but 

 specimens from the white shale show that the living chamber occupies 

 at least a volution. On these latter specimens, which are flattened 

 casts in a fine shale, the form of the aperture is preserved. The form, 

 as shown in the figure, is gently rounded at the sides, with a deep, 

 rather broad hyponomic sinus. The surface markings seen on the 

 hematite replacements found in the red shales have the same course as 

 the outlines of the apertures on the white shale. The markings, which 

 are very faint, sweep gently forward from the umbilicus, become 

 stronger on the sides of the shell and turn abruptly back on the venter, 

 forming very slight hyponomic ridges. 



The cameras are shallow, but not so shallow as those of the species 

 just described. In young stages the sutures are further apart and the 

 whorl-section more rotund. The course of the suture is shown in the 

 figure. The lobes and saddles are slightly deeper than those of 

 Tornoceras crebriseptiim. 



Four species of Tornoceras have been described from the Devonian 

 of New York state. From Tornoceras imia?igulare (Conrad) the 



