Review of the New York Geological Reports. 155 



strata, are Pentamerus, Eaomphalus, Hipparionix, a fucoid, in 

 the form of a cock's tail ; a trilobite with a forked tail, Odonto- 

 cephalus ; Cyrtoceras ; several species of Strophomena, Orthis, 

 Atrypa and Delthyris ; a variety of corals; some fossils consid- 

 ered to be defensive fin-bones of fishes; Asaphus, Ascidapsis, 

 Acanthaloma, Dicranurus. 



It does not appear that the Helderberg rocks have afforded any 

 valuable materials," except such as are employed in constructions 

 and agriculture. 



Some of the fossils of this group bear a striking analogy, if 

 they be not identical with a few of those which occur in the up- 

 per Silurian rocks of Murchison, and there is, perhaps, little doubt 

 but they are cotemporaneous deposites. 



The lithological character of the Erie division, as a whole, 

 is argillaceous, viz. black and blue shales at the base, with in- 

 tercalated thin beds of impure limestones in the middle, and 

 shale and grits above. 



The upper part of the Erie division passes by almost impercep- 

 tible gradations into the Catskill group, which is considered by 

 Mr. Vannxem to be equivalent to the old red sandstone of England. 



It consists of light colored, greenish-gray sandstone, usually 

 hard ; a fine-grained red sandstone, red shale or slate ; of grind- 

 stone grit ; and a peculiar concretionary and fragmentary mass, 

 like the cornstone of the old red sandstone of England. 



The group in question is rather barren in fossils. Two species 

 of Cypricardites have been found peculiar to it ; also, some re- 

 mains of a remarkable fish, considered the same as the Holopticus 

 of the Devonian system of England. Fossil plants are more 

 common in the Catskill group than shells or bones, giving rise 

 sometimes to coal, accompanied by pyrites, but they never exceed 

 one foot in length and breadth, and one inch in thickness. Until 

 the position and age of this rock was determined, strong hopes 

 were entertained that valuable seams would be discovered. " In- 

 stances are but too frequent where explorations have been under- 

 taken," says Mr. Vanuxem, " which have been attended with 

 much anxiety of mind, and have resulted in nothing better than 

 a waste of time and loss of money." 



The flora of the Catskill group shows an approximation or 

 transition to the true carboniferous era. Amongst those of un- 

 common form, we recognize some of the familiar family of Sigil- 

 laria, so abundant in the coal measures. 





