378 bulletin: museum of comparative zoology. 



Lower and Upper Carhoniferoiis in Montana. 



One of the problems in the study of the western Carboniferous is to 

 determine where the line between Upper and Lower Carboniferous 

 should be drawn. If fossils are to be used in reaching a decisi' ~ it 

 will be necessary to rely mostly upon brachiopods, for not only do 

 they include the great majority of all Carboniferous fossils, at least 

 in southwestern Montana, but the species are for the most part quite 

 easily identified. As a contribution toward the solution of this 

 problem I append lists containing all the brachiopods so far reported 

 from Old Baldy, Montana. They are separated into three groups; 

 the first contains those which occur in the Lower Carboniferous, the 

 second cont.ains those which occur in the Upper Carboniferous, and the 

 third contains those which are known to occur in both Upper and 

 Lower Carboniferous. In compiling these lists I have used the pub- 

 lished lists of Meek ^ and Douglass,^ and also the collections in the 

 Museum of Comparative Zoology made by Professor Woodworth and 

 his students in the Harvard Summer School. My own collections 

 were made while I was a member of the Harvard Summer School in 

 1915. Weller's Bibliographic index of North American Carboni- 

 ferous invertebrates^ was the chief source of information regarding 

 geologic ranges. There is much valuable information as to geologic 

 ranges in Girty's Carboniferous formations and faunas of Colorado.* 



Brachiopods occurring in the Lower Carboniferous. 



Schizophoria resupinata (Martin). 

 Leptaena analoga (Phillips). 



rhomboidalis (Wilkins). 

 Schuchertella crenistria (Phillips). 



inflata (White and Whitfield). 

 Orthotetes inaequalis (Hall). 

 Chonetes loganensis Hall and \Miitfield. 



ornatus Shumard. 

 Productus altonensis Norwood and Pratten. 

 flemingi var. liurlingtonensis Hall, 

 laevicostus White, 

 parviformis Girty. 



' Meek, 1873, Sixth Ann. repl.. Li. S. peol. surv., of terrilories for 1S72, p. 468-470. 



' Douglass, 1905, Aniiul.s CurnoKie mus., 3. p. 417-420. 



» Weiler, 1898. Hull. 153. L. S. G. S. 



« Girty, 1903. Prof, pap.-r Hi. V. S. G. S. 



