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Cincinnati Society of Natural History. 



In Vol. I. of Palceontology of New York, p. 62, was described a species 

 under the name of B. gracilis, Hall. In the second volume (p. 18), a 

 second species, the original having been called Fucoides gracilis, Emmons, 

 was called B. gracilis, and the one in the first volume was renamed, and called 

 B. tenuis. Under this second gracilis there were described at the same time 

 two varieties, viz., intermedia and crassa. Finally, in Vol. II., p. 263, B. 

 flexuosa was described. All these forms are closely allied, and though 

 from different horizons, seem referable to the same species. 



In the description of the B. gracilis, it is said that "scarcely any two 

 specimens are alike, and it is difficult to fix upon characters which shall 

 be decisive of specific importance." Professor Hall then goes on to show 

 the gradation from the delicate filiform branches of the species, through 

 ones with wider branches to the variety intermedia, and thence through 

 other grades to variety crassa. The form he called B. tenuis is evidently 

 intermediate between variety intermedia and variety crassa, and his B. 

 flexuosa seems to be a distorted specimen of crassa. Taking this view of 

 the species, they may be arranged as follows : 



Buthotrephis gracilis, Hall. 



var. intermedia, Hall, 

 var. tenuis, Hall, 

 var. crassa, Hall, 

 var. flexuosa, Hall. 



Thus there are three species reduced to one with four varieties, which 

 certainly cover the forms so far discovered. 



Now if Buthotrephis is not a plant, what is it ? To answer this ques 

 tion it will be necessary to go back a little. 



Some years ago, Professor Leo Lesquereux, of Columbus, described 

 from some specimens found in the rocks of the Cincinnati group of 

 Lebanon, a species which he named Psilophyton gracillimum. He referred 

 this to the Lycopodiaceae, a family of land plants represented during the 

 Carboniferous epoch by gigantic forms of vegetation Psilophyton is a 

 genus established by Dawson for certain plants with slender branches. 

 The figure of P. gracillimum shows a small, thin stem, with branches at the 

 top tapering to a point. (Plate 9, figure 5). It precisely resembles in 

 its essential features the figure of Buthotrephis gracilis, given by Hall. (Plate 

 9, figure 6). It is considered by Walcott {Tran. Albany Institute, Yo\. X., 

 p. 21), as a species of Dendrograptus, (P. gracillimum), and other palae- 

 ontologists have so regarded it. After describing two new species of the 

 genus Dendrograptus, and referring to the undoubted connection of 



