Ill 

 A\ ALGA FROM THE EOCENE OF COLORADO 



r. D. A. COCKERELI. 



In 1923, Professor Junius Henderson and Mr. John Byram 

 found a peculiar fossil plant in the Green River Eocene rocks of 

 the Roan Mountains, Colorado. Two specimens are from their 

 Station 25, on Kimball Creek; the other, with reverse, is from 

 Station 24, Roan Plateau. My first impression was that we had 

 a moss, but on using the binocular, the specimens having been 

 covered with water, it soon became apparent that the characters 

 were not at all those of a moss, but of an alga. No genus 

 of fresh-water algae can be found that is at all similar, but the 

 resemblance to certain of the marine Rhodomelaceae is so close 

 that the plant may be provisionally included in that family. 

 It offers one more indication that the waters of the lake were 

 saline and that the Green River aquatic fauna and flora were 

 remote descendants of a group of marine organisms isolated 

 by otogenic movements perhaps near or soon after the end of 

 the Mesozoic. The fishes long ago suggested such an idea; and 

 the peculiar Xantholithes of the Wyoming Eocene, mistaken for 

 Ophioglossum, may be another relic of this ancient group. 

 There may have been a deep rift containing a lake comparable 

 to Lake Baikal. The problem is a fascinating one and should be 

 fully investigated. At the present time many precious fossils 

 are to be found in the dumps of the many assessment holes in 

 the oil shale; in a short time all this material will have decayed 

 though fresh excavations may afford new opportunities. The 

 fossil may be described as follows: 



Phenacocladus new genus 



Small moss-like branches, bearing innumerable long capillary 

 filaments, not attached to the branches altogether at random, 

 but more or less distinctly verticillate; branches terminating in 

 one or two stichidia, the spores arranged in numerous rows, 

 apparently singular (not tetrasporic); stichidia oblong, obtuse, 

 resembling the capsule of a moss. 



Phenacocladus hendersoni n. sp. 



Stichidium when mature about 3.6 mm. long, and slightly 

 over 2 mm. broad; at an earlier stage narrower. Sporangia in 



