LOWER CARBONIFEROUS FOSSILS. 517 



Formation and locality: Madison limestone, Crowfoot Ridge, Gallatin 

 Range, bed 31; J. P. Iddings and W. H. Weed. 



ERIDOPORA Ulrieh, 1882. 

 Eridopora (?) sp. 



Quite abundant at the head of Conant Creek, Teton Range, on speci- 

 mens of Seminula maclisonensis, is a low incrusting bryozoau, whose exact 

 affinities among known forms I have been unable to determine. It seems 

 to be related to the genus Fistulipora. The colony is not maculate, the 

 cell walls rather thick, the cells very short, usually nearly square and 

 arranged in somewhat curving rows, about four in the space of 1 mm. 

 Often at the angle between four cells, sometimes situated laterally between 

 two of them, may be seen one or perhaps two minute interstitial cells, 

 which are not seen on the surface (!). Younger, or perhaps better pre- 

 served, parts of the colony show the terminal portions of the cells to be 

 cylindrical, slantingly superjacent, somewhat contracted at the circular (!) 

 aperture. It is owing probably to erosion that the distal portions of the 

 colony are missing, which leaves exposed below the angular crowded cells 

 of the colony, as seen under ordinary conditions. 



For a Fistuliporid the intermediate cells are extremely scarce. 



Formation and locality: Madison limestone, head of Conant Creek, 

 Teton Range; W. H. Weed. 



- 



PTILOPORA McCoy, 1844. 



Ptilopora sp. 



Zoarium, an extended, Fenestella-like frond. Reverse: Midrib large, 

 about 0.5 mm. in diameter, very prominent, cylindrical, without ornamenta- 

 tion except for a median row of strong distant nodes. Branches given off 

 pinnately at an angle of about 30°. Occasionally from these secondary 

 branches, branches of a third series are developed, but on the distal side 

 only, at the same angle (30°). The midrib is conspicuously larger than the 

 branches, which are uniform and about fourteen in 1 cm. Dissepiments of 

 nearly the same size as the branches, and, like them, without ornamentation. 

 Fenestrules square to rectangular, with an angular outline; about fourteen 

 in 1 cm. 



