Fossils of the Utica Slate. 21 



Dendrogeaptus tentjiramosus n. sp. 

 Plate I, figure 4. 



Stipe slender, compressed ; branches bifurcate from it irregularly, 

 frequently sub-dividing, terminating in filiform extremities ; surface 

 apparently smooth. Celluliferous side with smooth simple round 

 pits, or depressions along the center of the branches. Substance 

 corneous and as in Dendrograptm simplex probably tubular. 



The compression of the tubular stipe and branches forms a rim-like 

 margin on each side of a central depressed area in which the cellules 

 are seen, as in the specimen illustrated on Plate i, fig. 5, 5, a, b. 



The different mode of branching, the slender extension of the 

 branches and the general appearance of the entire frond distinguishes 

 it from the preceding species. From Dendrograptus {JPsilophyton) 

 gracillimum it is separated by having smaller cellules and less robust 

 stipe and branches. In specimens received from Mr. S. A. Miller of 

 Cincinnati, Ohio, identified as the Psilopjhyton gracillimum of 

 Lesquereux, the cellules are larger and more elongated than in the 

 species from the Utica slate, the stipe and branches show the same 

 compression of an aj^parently corneous, hollow, tubular structure. 



The resemblance of these two species of Dexdeogeaptus to Lyco- 

 podiaceous plants of the genus Psilophytox is very striking and apt 

 to mislead the observer. Their occurrence with algse, graptolites, 

 trilobites and brachiopods in the same layers of shale, in a posi- 

 tion indicating their growth in situ, taken with their graptolitic 

 structure, precludes the idea of their being of other than marine 

 origin. 



Formation and locality, TJtica slate, town of Trenton, Oneida 

 Co., N. Y. 



Dexdrogkaptus compactus n. sp. 

 Plate I, figure 1. 



Frond fan shaped ; branches comparatively coarse and numerous ; 

 stipe below the branches unknown. 



The specimen figured is the only one in the collection ; it is too 

 much weathered to show the surface characters. The shape of the 

 frond and the numerous and compact branches distinguish it from 

 allied species of the same genus. 



Formation and locality, Utica slate, town of Trenton, Oneida 

 Co., N. Y. 



