2 PALEONTOLOGY OF NEW-YOKK. 



We shall therefore commence our descriptions with those organic forms which are typical 

 of the acknowledged base of the pala-ozoic series on the American continent, leaving for 

 future consideration those forms Avhich have given rise to some difference of opinion 

 regarding the age of the rocks in which they occur. Further explorations may add to the 

 number of forms already known in this rock ; but it must be acknowledged, that, thus far,, 

 it has proved very barren in organic products. 



ORGANIC REMAINS OF THE POTSDAM SANDSTONE. 



Plate I. 



Genus SCOLITHUS. 

 [ From the Greek, rfx^Xrig, a worm, and Xiflo?, a stone.] 

 Skolithus. Haldemait, Supplement to No. I. of a Monograph of tlie Limniades, &c. 1S40. 



This name was first proposed by Professor Haldeman, as forming a sub-genus under 

 FucoiDES, and is now recognized by him as forming a distinct genus. 



Character. Stem free, simple, cylindric or subcyiindric, vermiform or linear, never 

 branched. 



1. 1. SCOLITHUS LINEARIS. 



Plate I. Fig. 1. a. b. c. 



Stem simple, rectilinear ; surface nearly even, cylindric or compressed, sometimes 

 apparently striated. 



Diameter ^ to ^ an inch ; length from a few inches to several feet. 



This fossil, in its usual aspect, presents the appearance of numerous linear stems, often 

 extending to one or two feet in length. Ordinarily it appears like a series of small pins or 

 pegs driven into the rock in a somewhat regular manner, and at uniform distances. It 

 preserves its distinctness even when the surrounding rock is much altered, as along the 

 western face of the Green Mountains. In such situations, and often in others, the fossil is 

 stained by oxide of iron, and the rock cleaves more easily in that direction. 



In tlie Second Annual Report of the Geology of Pennsylvania, Prof. Rogers speaks of 

 this " marine plant " as the best defined species discovered in this rock. He has also spoken 

 of it under th(> name of Tubuliics ; but I believe no generic description ever appeared, 

 previous to the one of Prof. Haldeman ; nor am I able to find in print tlie name tubulites 

 applied to this fo.ssil, of anterior date. 



Fig. 1. a. A vertical or longitudinal view of a specimen of the rock containing these bodies. 



Fig. 1. A. A similar view of a specimen of partially altered and laminated sandstone from Pennsylvania, 



the tubes somewhat flattened. 

 Fig. 1. c. Weathered surface of a specimen of the altered sandstone (crystalline or granular quartz), from 



Adams, Mass. 



