540 PALAEONTOLOGY OF ILLINOIS. 



obscured by the shale; generally twice as long as wide, 8.5 in 

 1 cm. On the reverse the branches are rounded and distinctly 

 striated longitudinally. 



The compressed branches, large fenestrules, small and widely 

 separated cell-apertures, and numerous nodes on the keel, are 

 the distinctive features of this species. Its frond has a more 

 delicate look than any of the associated forms. 



Position and locality: Keokuk group. King's Mountain Tun- 

 nel, Ky. I have collected several fragments of this or a very 

 closely allied species from the Chester group at Sloan's Valley, 

 Ky. ' 



FENESTELLA COMPRESSA var. NODODORSALIS Ulrich. 



PI. L, flg. 2. 



This name is proposed, provisionally, for a form of which I 

 have seen only one example. This is over 8 cm. in length by 4 

 cm. in its greatest width. It adheres tightly to a slab of lime- 

 stone from King's Mountain, with the reverse, which is finely 

 preserved, exposed. As it agrees fairly well in the strength of 

 its branches, form and size of its fenestrules, with F. compressa, 

 I at first supposed that it represented the reverse of that species. 

 Having occasion to prepare some thin sections of the type speci- 

 mens of F. compressa, I was surprised at seeing no indications 

 of a tuberculated reverse. This discovery led to an examina- 

 tion of all the specimens I had referred to the species. The 

 result was that the reverse of all the specimens, excepting the 

 one in question, was found to be simply rounded and even. A 

 careful comparison shows that beside the strong and irregular 

 nodes, there are also slight differences in the measurements. 

 Thus, while F. compressa has fourteen or fifteen branches and 

 8.5 fenestrules in 1 cm., this specimen has twelve or thirteen 

 branches, and 7.5 to 8 fenestrules to that space. Under these 

 circumstances it seenls best to refer to it as above. 



FENESTELLA MTJLTISPINOSA Ulrich. 



PL L, Figs. 3-3e. 



Zoarium a strongly undulating flabellate expansion. The 

 largest example seen (it is nearly perfect) measures in different 



