Vaughan — Outlying Areas of the Comanche Series. 49 



clay, containing carbonaceous particles and resting against the 

 Red Beds. This clay is probably Cretaceous. 



On Section 10 of the same township and range, another out- 

 crop of the shell limestone was seen. Mr. H. G. Springston 

 told me that other outcrops occur on sections 7 and 8 of T. 19 

 N., E. 17 W. 



Marcoi^s Comet Creek locality. 



This locality is especially important because it is the original 

 locality at which Marcou found his Gryphwa pitcheri, and is 

 the type locality for his Neocomian. 



Marcou states " I have mentioned two points between 

 Topofki Creek and Anton Chico where the Triassic rocks are 

 covered by more modern formations. The first of these points 

 is upon one of the tributaries of the False Washita river — 

 Comet Creek (latitude 35° 32' 2" ; longitude 99° 14' 40")— 

 near our camp No. 31, where upon the heights are found the 

 remains of beds of a limestone filled with shells, which I con- 

 nect with the Neocomian of Europe, or in other words with 

 the Lower Division of the Cretaceous Rocks. This limestone 

 is only five feet thick ; it is of a whitish gray color, containing 

 an immense quantity of Ostracea, which I consider as identical 

 with the Exogyra {Gryphwa) Pitcheri Mort. (PL iv, Hg. 5, 5a, 

 5b and 6) having the closest analogy with the Exogyra Couloni 

 of the Neocomian of the environs of Neuchatel (Switzerland)."* 

 On page 39 of the Geology of North America, Professor 

 Marcou gives long. 99°, lat. 35° 50', one of the hills surround- 

 ing Comet Creek, as the original locality of his Gryphwa 

 pitcheri (not Morton^s G. pitcheri) — G. forniculata (White). 

 There is a discrepancy between these two records of the Comet 

 Creek locality. Marcou's Geological Map of the routef intro- 

 duces another discrepancy. The following can be obtained 

 from studying what he has written or represented on his map. 

 The locality is not far from Arapaho, it is near the Washita 

 Piver and is on its northern side. Upon comparing Marcou's 

 map in the Pacific Pailroad reports with the present postal 

 route map, it seems very probable that what Marcou called 

 Comet Creek is now known as Barnitz Creek. If Marcou had 

 stated upon which side, east or west, of Camp 31, or upon 

 which side of Comet Creek the locality was, we might be able 

 to rediscover it without great difficulty. 



I found eighteen miles north of Arapaho, about two miles 

 south of the T> and G county line, an agglomerate composed of 

 G. forniculata. Mr. G. T. Dulany, superintendent of schools 



* Geology of N. A., p. 11, 1858. 



f Vol. iii, Senate Doc, Report Pac. R.R,. Expl. 



Am. Jour. Sol— Fourth Series, Vol. IV, No. 1.— July, 1807. 

 4 



