1877.] OoO [Sadtleiv 



Elevation of external cusp 065 



internal " 055 



Length between apices of external cusps 043 



The molar tooth described exceeds in transverse dimensions that of th& 

 Mastodon ohioticus, and evidently belonged to one of the most colossal of 

 land animals. Its generic position is near to Mastodon and Dinotlierium, but 

 if the tooth on which my observations are based be complete, it is distinct 

 from either. The possession of only two transverse crests separates it 

 from the former, and would, were tlie tooth an anterior molar, refer it to 

 the latter. As it appears to be a posterior molar, this view of its affinity 

 becomes untenable, and I therefore establish for it a new genus, under the 

 name CiENOBASiLEUS. The tooth described resembles that of the genus 

 Tapirus, but differs in the absence of the external trihedral enlargement 

 of the cross crests seen in the superior molars of the former, and also in 

 the tubercular and fissured character of the crests proper. The species 

 may be called C. tremontigerus. 



The typical specimen was probably obtained in Texas, but I am not yet 

 informed as to the precise locality. 



CONTRIBUTIONS FROM THE LABORATORY OF THE UNIVER- 

 SITY OF PENNSYLVANIA. 



No. VIII. 



On the Composition of the Natural Gas from certain Wells in Western- 

 Pennsylvania and New York. 



By Samuel P. Sadtler. 



{Bead before the American Philosophical Society, March 2, 1877. ) 



In February, 1876, I read before this Society a paper giving some re- 

 sults obtained in the analysis of the natural hydrocarbon gases of "Western 

 Pennsylvania. The material examined at that time consisted of the gases 

 from thq Burns Well and the Harvey Well in Butler Co., from the Rogers 

 Well in Westmoreland Co., and the Cherry Tree Well in Indiana Co. 



During the past summer I was again engaged in the service of the 

 Second Geological Survey of the State, and spent a month in the Oil re- 

 gions of Pennsylvania. While on this trip I collected six new lots of 

 natural gases and have recently completed my examination of them. 



These gases were the following : 



1. A new sample from the Harvey Well in Butler County. This was 

 taken as in the previous case from the delivery pipe in Spang, Chalf\int «& 

 Co.'s Mills at JEtna, Alleghany County, Pa. An interval of nine months 

 had elapsed and I wished to see if any differences in its chemical composi- 

 tion could be made out as having occurred in the meantime. 



2. From a Well near Sheffield Station on the Philadelphia and Erie 



