GRAPTOLITES OF THE HUDSON VALLEY. o.".!) 



Dicellograptus divaricatus, Hall. 



sextans, Hall. 

 Dieranograptw ramosus, Hall. 

 " furcatus, Hall. 



ramosus, Hall. 

 Glimacograptus parvus, Hall. 

 typicalis, Hall. 

 scalar is, Hall. 

 Diplograptus angustifolvus, Hall. 

 marcidus, Hall. 

 pristis, Hall. 

 putillus, Hall. 

 secalinus, Eaton. 

 spinulosis, Hall. 

 tvhitfieldi, Hall. 

 " mucronatus, Hall. 



Retiograptus barrandei, Hall. 



geinitzianus, Hal 1 . 

 Thamnograptus capillaris, Hall. 

 " typus, Hall. 



Of the preceding species, Didymograptus serratulus, Hall ; Dicellograptus 

 divaricatus, Hall; Dicranograptus ramosus, Hall; Glimacograptus bicomis, 

 Hall (doubtful); Climacograptus typicalis, Hall; Climacograptus scalaris, 

 Hall; Diplograptus pristis, Hall; Diplograptus putillus, Hall, and Diplo- 

 graptus mucronatus, Hall, occur in the Utica shale of the Mohawk valley, 

 and Diplograptus amplexicaule of the Trenton limestone is found in the upper 

 portion of the Lorraine section. 



In the third volume of the Paleontology of New York, 1859, Professor 

 Hall describes the Hudson River group, as known to him in the Mississippi 

 valley and Canada. He says : * 



" The group of strata known as the Hudson River group, which in its more ex- 

 tended signification may include all the beds from the Trenton limestone to tho 

 Shawangunk conglomerate, has afforded in New York but small additions t'> tin' 

 number of fossils previously known in this formation." 



In 1862 f Professor Hall concluded from the results of the extended study 

 by the Canadian geologists, especially Sir William Logan, thai the strata 

 referred to the Hudson River group in the valley of the Hudson belonged 

 to an older geologic epoch than that referred to the same group in western 



*Loc cit., p. 1 1. 



fKep. Geol. Survey, Wisconsin, vol. 1, 1862, p. 17 (foot Dote) 



