NORTE AMERICAN GRAPD OLIMIES': 
NEW SPECIES AND VERTICAL RANGE." 
PREFACE. 
No general revision of American graptolites has been 
attempted since the termination of Hall’s classic labors some 
thirty years ago, and one based on the lines of recent taxonomic 
progress is badly needed. The present paper is a preliminary 
attempt at such a zoGdlogic and geologic revision. 
The tables showing the vertical range of species are, to a 
considerable extent, based on my own determinations. This 
reservation is necessary, as many of the ranges assigned to species 
are incorrect, the result of erroneous identification. In this 
matter I am glad to find myself in general accord with Ami,’ 
almost the only American observer who has studied extensively 
the graptolites in the light of recent foreign work. 
A word as to the somewhat numerous changes made in the 
synonymy. Most of them are in accordance with general grap- 
tolite consensus. Most of the remainder are explicable on the 
ground of priority. Ina previous paper3 I followed general con- 
sensus rather than attempt the necessary thorough overhauling 
of the synonymy, reserving the latter until such time as I could 
publish more extensively the reasons for the requisite changes. 
Now, however, it seems best to enforce priority rigidly, and to 
this end the original spelling has been followed in all cases. 
Reasons for deviation from current usage are given in brief, but 
in a paper of this compass it is of course not possible to give the 
evidence in extenso. 
No attempt has here been made to determine accurately the 
* Published by permission of the Director of the U. S. Geological Survey. 
2 Bull. Geol. Soc. Amer., II., pp. 477-502, Plate XX. 
3Ann. Rep. Geol. Surv. Ark. for 1890 (1892), III., pp. 401-418, Plate IX. 
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