338 CARBONIFEROUS FORMATIONS AND FADNAS OF COLORADO. 



POLYPORA Cf. D18TINCTA Ulrich. 



1890. I'oliipoM dixI'nicUi. Ulrich, Geol. Surv. Illinois, Kept., vol. 8, p. G03, pi. (il, figs. 7, 7a. 

 Upper Coal Measures: Springfield, 111. 



This is a rather coarse form, characterized by somewhat lax and irregular growth. 

 The branches are strong, and connected by dissepiments which are slender, .short, 

 and situated at distant intervals. The zooecia are arranged in four, possiblj' in live, 

 longitudinal rows. Their apertures have elevated margins and they manifest a 

 certain tendency toward, or appearance of, dimorphism, for, scattered among the 

 regular zooecia, are a number of others which are often of smaller size, or, when 

 equal, seem by their proximity to them to be arranged in groups of two. The non- 

 porifei'ous side has not been seen. 



This form is not identical with P. ddstvncta but is probably no more than a 

 variety. It is also allied to P. gracilis Ulrich. 



Locality. — Leadville district (station 2265). 



PoLYPORA cf. CESTRiENsrs Ulrich. 



1890. Polypora cesiriensis. Ulrich, Geol. Surv. Illinois, Rept., vol. 8, p. 59-1, pi. 55, figs. 4-46; pi. 60, 

 figs. 7-7c. 

 Chester group: Chester, Kaskaskia, and near Anna, 111.; Litchfield and Sloans Valley, 

 Kentucky. 

 1895. Polypora cestnensis. Keyes, Missouri Geol. Surv., vol. 5, p. 29. (Date of imprint, 1894.) 

 Kaskaskia limestone: Ste. Genevieve, Mo. 



This is a coarsely reticulated . form with elongate elliptical f enestrules. The 

 zooecia are in four rows. The nonporiferous side is ornamented with sharp but 

 rather fine longitudinal strise. The poriferous side also is marked by ridges which 

 pass between the zooecia and in some degree define them. 



Ziocallty and Tiorizon. — San Juan region (station 2331); Hermosa formation. 



Polypora n. sp. 



This form is represented by a fragment of a frond from the Leadville region, 

 and by two fragments, each from a different locality in the San Juan region, which 

 probably belong to the same species. My material is too fragmentary and ill pre- 

 served to permit a detailed description of what is probably a new species. 



The frond is rather coarsely reticulate with thick branches and short, thin dis- 

 sepiments. The fenestrules are elongate elliptical. The branches are carinated on 

 the nonporiferous side and marked bj' moderatelj^ fine, sharp strife. The zooecia 

 are in three or four rows and their apertures have elevated margins. 



Locality and horizon. — San Juan region (stations 2331?, 2832); middle portion 

 of the Hermosa formation. Leadville district (station 2268). 



