Raymond : Fauna of Upper Devonian of Montana. 147 



ear on the posterior end of the left valve, a ligamental area under the 

 umbos, concentric ridges on the right valve, and in the absence of 

 broad radial ribs, and of a posterior opening between the shells. In 

 surface markings, disregarding the concentric wrinkles on the right 

 valve, our specimens agree best with figures 4/^ and 4^/-4/ of the 

 illustrations in Freeh's work cited above, while Dr. Clarke's specimens 

 seem to agree best with figures 4c, 4^ and 4/1. Loxopteria torrugata 

 Clarke and L. rugosa Freeh are species with pronounced concentric 

 wrinkles on the right valve, but neither of these species has a sharply 

 defined posterior wing. 



This species is named for Professor Eduard Holzapfel, of Aachen, 

 whose researches have greatly extended our knowledge of the Upper 

 Devonian faunas. 



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

 Upper Devonian at Three Forks, Montana. It occurs more rarely in 

 the limestone above the red shale at the same locality. 



Loxopteria clarkei sp. nov. 



(Plate V, figures 8-10, 12-17.) 



Cf. Kochia ( Loxopteria ) hrvis Freeh, 1 891. " Die Devonischeti Aviculiden Deutsih- 

 lands ; Abhaiidliingen zttr geohgischeii Specialkarte von Preuisen mid den Thih'- 

 ingischen Siaateti,^' Band IX, Heft 3, p. 76, t. 6, figs, j-jif. 



Just as Loxopteria holzapfeli is closely related to L. dispar, so the 

 other species of Loxopteria found in the same fauna is very similar to 

 L. Icevis Freeh. The shell may best be described by comparing it 

 with the species of this genus already known. Both valves are con- 

 vex, there being much less disparity between them than in L. holzap- 

 feli. From that species it differs also in having a less highly elevated 

 and more rounded umbonal region, a less acute and prominent beak 

 and in the possession of concentric undulations on both valves. 



From Loxopteria Icevis it differs in having a more pronounced pos- 

 terior wing on both valves, a less depressed beak on the left valve, and 

 in the presence of concentric undulations on both valves. 



Dr. Clarke has referred to Loxopteria Icevis specimens which, as 

 that author remarks, differ considerably from the German specimens 

 in having a depressed right valve and concave larval shell. None of 

 the shells from Montana show these characters. 



This shell is named for Dr. John M. Clarke, to whom we are in- 

 debted for our knowledge of the fauna of the Middle Upper Devonian 

 of America. 



