12 PENNSYLVANIA AND NEW YORK DEVONIAN. [bull. 120. 
It is true that Spirifera disjuncta Sow. is reported from this forma- 
mation; l and if the specimens were correctly identified that would be 
almost conclusive proof of its Chemung age. But the writer has failed 
to find this species on the eastern side of the Pocono and Catskill 
mountains and is inclined to think that Spirifera mesastrlalis Hall, an 
allied species which is not uncommon, is the one reported for S. dis- 
juncta, especially since the Cascade section of Susquehanna County, 
Pa., has been reported to contain well-known Chemung shaly and 
flaggy strata full of Spirifera disjuncta. 2 When the section was exam- 
ined, in company with Dr. H. S. Williams, it was found that the com- 
mon species was S. mesastrialis, which had evidently been mistaken 
for the S. disjuncta. 3 
After considerable field work in southeastern New York and north- 
eastern Pennsylvania, the conclusion is reached that the marine faunas 
terminated either slightly in advance or soon after the appearance of 
the Chemung stage. In central and southern Pennsylvania and west- 
ern Maryland the conditions seem to have been more favorable, and 
Spirifera disjuncta with other Chemung species occurs in rocks which 
are stratigraphically equivalent to the unfossiliferous beds farther 
toward the northeast. The geological collections of Johns Hopkins 
University contain a few specimens of Spirifera disjuncta from near 
Cumberland, Md., 4 and Profs. Claypole/' White, 6 Stevenson, 7 Ash- 
burner, 8 and Meek 9 have reported the species from a number of locali- 
ties in Pennsylvania and Virginia. 
The shales and sandstones of the Chemung series, which contain the 
highest fossil shells seen by Prof. White, are succeeded by greenish- 
gray, thick-bedded sandstones — the Starucca sandstone of Prof. White 
— which at that time he considered the base of the Catskill. 10 Later, 
Prof. White states " it seems probable that the 600 feet of grayish- 
green beds at the top of the Chemung in Pike and Monroe, which in 
G6 were referred to the Catskill under the name of Starucca beds, may 
be the equivalent of a portion of the Upper Chemung of this district 
[Susquehanna River region], and therefore erroneously referred to the 
J G6 p. 105? 
: G 5 , p. 78. 
3 See the remarks on the Cascade section by Dr. Wllilams, who states : ' ' When I examined the sec- 
tion I found no trace of several of the species cited, and only rare and imperfect specimens of Spiri- 
fera disjuncta and the last stage with Rhynchonella contractu ; but all the mass of the fauna was Spiri 
/era mesastrlalis and its legitimate associates, which is a lower fauna belonging to the more eastern 
part of this general area. The difference between the two Spiri/eras appears at first glance slight; 
but they are clearly distinct.'' (Proc. Am. Assoc. Adv. Sci., Vol. xxxiv, p. 231). 
<See list of Chemung fossils from Maryland, by Charles R. Keyes, in Johns Hopkins Univ., circu- 
lars, Vol. xi, December 1891, p. 29, which specimens, through the courtesy of Dr. W. B. Clark, have 
been personally examined. 
5 F 2 , pp.74, 77, 289, 291. 
f T3,pp. 98, 183, 194. 
'T 2 , pp. 76, 80. 133, 212. 214, 216, 225, 226; and Amer. Geol., Vol. ix, pp. 10, 26. 
s F,pp. 221, 225. 
9 Bull. Phil. Soc. Washington. Vol.ii; Appendix, art., viii, p. 34. 
10 G 6 , pp. 102, 103. See G 5 , 1881, pp. 59, 70, 73, and fig. 10 on p. 77 for the original description of 
this zone. 
