NO. 1141. FOSSIL CYC ADS FROM THE BLACK HILLS— WAHD. 229 



is related to G. niinneJiaJifensis tiiul C. inilchernma., and from it to C 

 mchridei, as already remarked, the distance would be very small but 

 for the branching habit of the former. 



Between G. mchridei and G. marshinna, however, there is scarcely 

 any bond, and it might have been as well to place the latter immedi- 

 ately after G. coJossaUn. We virtually begin a new series here and 

 pass naturally through G. furcaia to G. colei and G. paynei. G. aspera 

 closely resembles the last of these in external aspect, but the two 

 anomalous characters noted clearly distinguish it from all others. It 

 fits in here, however, and G. insoUta and G. occidentalis belong to this 

 same general group. 



G. jenneycma, G. iugenfi, G. formosa, G. stillicelli, and G. crcelsa may 

 also be said to form a group. The first and the last two constitute 

 the only cylindrical forms known in America. The shape of the scars 

 in G. ingens, G. formo.m, and G. stillicelli unite these three from that 

 important point of view, while those of G. jenneyana and G. infjens tcTul 

 to approach each other. G. exceha has little in common with any 

 other species, and G. nana almost nothing. These two are therefore 

 properly made to close the series. 



