364 CHARLES S. PROSSER 



Hamilton, 8 identical, 6 affiliated; Sherburne, 2 identical, 3 affiliated; 

 Ithaca, 8 identical, 3 affiliated; and the Chemung, with 3 identical, 

 and 2 affiliated. It will thus be seen that, so far as this fauna is con- 

 cerned, it indicates the correlation of this shale with the Marcellus 

 shale and Hamilton beds of New York, with the evidence somewhat 

 in. favor of the Marcellus, since it contains 10 identical species to 8 

 in the Hamilton. The weight of evidence in favor of correlation 

 with the Marcellus shale is strengthened when the list is examined 

 a little more closely. Liorhynchus limitare (Vanuxem), which, so 

 far as I am aware, is confined to the Marcellus shale in New York, 

 and perhaps may be considered its most characteristic fossil, or at 

 least its most distinctive Brachiopod, is found generally in the black, 

 fissile shale constituting the lower part of the Romney formation in 

 Maryland. Bactrites aciculatus (Hall) is known only in the Mar- 

 cellus of New York, and the Agoniatites expansus (Vanuxem) is so 

 characteristic of a thin layer of limestone in the lower Mg,rcellus of 

 New York that it has been named the Agoniatite limestone. In 

 Maryland 17c feet or more above the base of the black shales are thin 

 limestones which also contain Agoniatites expansus (Vanuxem). 



Finally, it may be said that, so far as the paleontological evidence 

 is concerned, it shows a close relationship between the Maryland 

 black shales and the Hamilton beds of New York, and Dr. John M. 

 Clarke has already shown that such a relation exists in New York, 

 since a large percentage of the species found in the Marcelhis shale 

 of that state occurs in its Hamilton beds.^ The paleontological 

 evidence, however, shows a still closer relationship with the Mar- 

 cellus shale fauna of New York, which is supported by the visible 

 continuity, lithologic similarity,^ and stratigraphic position of the 

 containing shales, so that the correlation of this Maryland black shale 

 with the Marcellus shale of New York appears to be fairly well sus- 

 tained. 



CORRELATION OF THE HAMILTON BEDS. 



The rocks overlying the Marcellus shale of the Romney formation, 

 and extending northeasterly from northern West Virginia across 



1 Eighth Annual Report of State Geologist of New York, 1889, pp. 60, 61. 



2 For a summary of the various methods of correlation see Mr. Gilbert in Compte 

 rendu, Fifth Session, International Geological Congress, 1893, pp. 151-54. 



