Notes on" the Geology of Yates County, N. Y, 197 



probable ; and, if it is correct, the plant is a true Equisetides, and the 

 present specimen is the first occurrence of this genus in beds older 

 than the carboniferous. It is to be observed, however, that Unger 

 has described from the Cypridi?ia-s\a>tes of Thuringia plants of the 

 genera Kalymma and Aster ophyllites (A. coronata) with sheaths at the 

 nodes ; and my A. scutigera, from St. John's, has verticils of scales at 

 the joints, which may represent sheaths. The present species has a 

 remarkable resemblance in its markings and the form of its sheaths 

 to a greatly magnified stem of the modern Equisetum fluviatile, 

 except that the leaves of the sheaths are shorter." 



"The species is named in honor of its discoverer. Its essential 

 characters will be as follows :" 



" Stem stout, cylindrical or broadly ribbed: surface marked with short 

 hairs or tubercles regularly arranged. Sheaths at the joints, of about 

 twelve leaves, of the general form of those of Eqiasetumfluviatile." 



'•'The specimen is from the Chemung group (Upper Erian) of Italy, 

 New York." 



Somewhat higher up we found Cyclostigma affine, Dawson, the de- 

 scription and figure of which quoted from the same source as above- 

 named, we herewith give below : 



Cyclostigma affine. 



Plate XV — Figs. 4, 5. 



" Stem marked with alternate circular leaf-bases or areoles, slightly 

 prominent below, evanescent above, and each with a circular dot or 

 vascular mark. Scars scarcely two millimetres in diameter, and sepa- 

 rated by finely corrugated bark, about twice their diameter apart. 

 These markings occur on a stem about an inch in diameter. The 

 Knorria, or decorticated form of this plant, presents irregular wav- 

 ing ridges, produced by the longitudinal confluence of the oblique 

 vascular bundles." 



" This plant is the nearest approach to the well-known G. kiltorkense 

 of Ireland, hitherto found in America. It differs chiefly in the more 

 closely placed areoles. It was collected by Mr. Wright, and is from 

 the Chemung (Upper Erian) of Italy, New York. The study of this 

 plant has led me to the belief that Stigmaria exigua of my report of 

 1871 may, when better known, prove to be a new species, allied to the 

 present, and a member of the genus Cyclostigma." 



In some of the coarse shales the little Amboccelia umbonata, var. 

 gregana, Hall, occurs to the entire exclusion of every thing else. 

 Discina Alleghania, Hall, Orthis carinata, Hall, 0. tioga, Hall, occur 

 sparingly, while large slabs are readily obtained that are filled with 

 Atrypa hystrix, Hall, without spines, and associated with Strophodonta 

 Gayuta, Hall. 



