Brown — Silurian Limestone of Mileslmrg Gap. 87 



Strophomena rugosa, Spirifer perlamellosa (?), Trematospira 

 (?), Zaphrentis, Corals. 



In 1892, J. P. Lesley in the final report of the survey 

 referred to this region, quoting from d'Invilliers and Ewing 

 the observations given above. This seems to be the latest pub- 

 lished description of the region.* 



The author's attention was first attracted to these beds when 

 Dr. E. S. Moore, of State College, called upon him to help 

 identify a small collection of fossils from these limestones. At 

 once it became apparent that there was considerable confusion 

 in the terms applied to these beds and some error in their 

 interpretation. A study of the fossils above mentioned was 

 supplemented by visits to outcrops in the field, where a consid- 

 erable collection of fossils was made and the outcrops carefully 

 studied. 



The beds referred to by d'Invilliers as No. YI, or Lower 

 Helderberg, in reality contain representatives of more than one 

 horizon, the lower part being equivalent to the Decker Ferry 

 of northeastern Pennsylvania and New Jersey and the upper 

 part containing a typical Oriskany fauna, which is identical 

 with that found in the sandstone above. 



The lowest distinct limestone bed which outcrops on the 

 first little ridge north of the gap and southwest of Milesburg 

 (fig. 1-B, bed 5) yielded a good fauna, although largely com- 

 posed of corals, in which the following species have been iden- 

 tified. 



Diphyphyllum integumentum Barrett. 



Cladopora rectilineata Simpson. 



Cladopora btfurcata Grabau. 



Favosites pyriforme Hall. 



Fwosites corrugatus Weller. 



Halysites Catenularia (Linn). 



Proetus pachydermatus Barrett. 



JProetus spinosa Weller. 



In addition to these there were several Cyathophyllum-like or 

 Zaphrentis-like corals which have not yet been identified. 

 Several of these show carinse and may be identical with those 

 described by Grabau from the Monroe beds of Michigan. 



Of the above mentioned species Cladopora rectilineata is by 

 far the most abundant, and is no doubt the form referred to 

 by Rogers when he said that: "The Pre-meridian or upper 

 division of the limestone is filled with carved and delicately 

 formed corals, visible only on weathered surfaces." Along the 

 crest of this limestone ridge certain thin beds are composed 

 almost wholly of this coral. Brachiopods are sparingly repre- 

 sented here although no specimens were obtained in such con- 

 dition that they could be identified. 



* Summary Final Eeport, vol. ii, p. 1002. 



