FOSSILS OF THE UTICA SLATE. 



[Read before the Albany Institute, March 18, 1879.] 

 By C. D. Walcott. 



It is not designed under the above title to present a detailed 

 description of the various fossils found in the Utica slate formation, 

 but to give a list of those occurring in it, with references to publi- 

 cations where descriptions of the species mentioned may be found ; 

 also descriptions of some new species not hitherto known in the for- 

 mation, and a notice of the development, or metamorphoses as far as 

 now known, of its characteristic trilobite Triarthrus BecM. 



CYATHOPHYCUS nov. gen. 



Kua&off — a cup y ^Z-K^c, — a sea weed. 



Hollow membraneous fronds with an opening at the upper extrem- 

 ity of the frond, elongate or hemispherical in form ; reticulate or 

 plain structure. 



The type of the genus Cyathophyciis reticulatus, resembles in its 

 tubular, hollow, membraneous frond, with a recticulated structure, 

 the recent genus of algae Enteromoepha. 



CyATHOPHTCUS KETICtJLATUS fl. Sp. 



Plate II, figures 16, 16 a — d. 



Elongate, tubular, hollow fronds ; membraneous, with a strong 

 reticulated structure ; opening at the summit circular, usually a 

 little smaller than the diameter of the frond, and sometimes with a 

 thickened margin ; the thickened cell walls are arranged in longitu- 

 dinal and transverse lines, giving the reticulated appearance, even 

 in poorly preserved specimens. 



The longitudinal lines of cell walls converge and unite at th^ base 

 to form a short obtuse stem or root. 



The fronds vary in length from one and one-half to twenty-three 

 centimetres and in form from long tubular to broad cup shaped. 



This rare and beautiful alga is associated with graptolites ; — Den- 

 DEOGRAPTUS, Climacograptus — Endocevas proteiforme and Triar- 

 thrus Becki. Specimens of a small undetermined Pleurotomaria 

 are attached to several fronds. 



