The Paleontologist. [July 2, 1878. 



THE TWO FOLLOWING SPECIES ARE FROM THE 

 UPPER SILURIAN ROCKS. 



Ptilodietya fimbriata- (sp. nov.) (James.) Polyzoary consisting of two edge 

 fronds, branching dichotomously and trichotomously ; branches and main stem of equal 

 or nearly equal width, except at the branching points where the width is greater; branches 

 generally curving or flexuous, edges thin and sharp. Central rows of cells oval, five or six 

 in the space of a line measuring longitudinally, and ten in the same space transversely ; 

 interspaces about equal to the cells and occupied by more or less of very minute pores. Cells 

 arranged between longitudinal lines, ten or twelve rows on each branch, in two or three of 

 which, near each edge, the cells are larger than the others, more elongated and have an 

 ol)lique direction. 



The marked feature of this species is the I'ery finely striated poriferous edges of the 

 branches, giving them a beautifully fringed appearance. In this respect it differs from the 

 Generic description of Ptilodietya, but in all other features it seems to agree. 



The Polyzoary from which this description is made is three inches broad just above 

 the middle and nearly two and a half inches from base to top. It is partly imbedded in 

 a fragment of rock, the exposed surface somewhat worn, the base of the cells of the other 

 side are shown in some places. 



Position and Locality. Upper Silurian, Clinton or Niagara Group. My son (Davis) 

 found the specimen at a locality in Clinton Co., Ohio, where there is a thin outcrop of the 

 Clinton Group between the upper bed of the Cincinnati group and the lower bed of the 

 Niagara group. 



Ptilodietya- (sp. ?) This species branches out from the base somewhat like the 

 preceding, but the branches are wider and closer together, in some places almost touching 

 each other. Edges of the frond non-poriferous. Cells arranged longitudinally between 

 sharp delicate lines. The specimen has been split longitudinally, nearly in the center, 

 showing, in some parts, the central axis. It is imbedded in a fragment of rock. 



This species resembles P. excellens Billings from the island of Anticosta. but it does not 

 seem certain that it is identical. The '■^ small pits'''' at the ends of the cells are more numer- 

 ous than refered to that species, and they extend to other parts than at the ends, arid in 

 some cases spreading around the cells. The Polyzoary consists of twelve branches, hav- 

 ing a somewhat triangular outline, the base at one of the corners, but a small portion of 

 the top has been broken away. 



Should this prove a distinct species, I propose the name of Welshi for it [Ptilodietya 

 Welshi), in honor of Dr. L. B. Welsh, of Wilmington, Ohio. 



Position and Locality. Upper Silurian Formation, Clinton Croup, Clinton Co., O. 



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