TITLES AND ABSTRACTS OF PAPERS 95 



New York. As no break occurs at the base of the Martiiisburg, the interval of 

 folding and erosion indicated by the unconformity above mentioned came later, 

 the exact time being unknown at present. After the erosion interval followed 

 more shale deposition, the new deposit overlapping the Lower Martinsburg and 

 all the older formations that had been truncated by erosion. 



The upper part of the Martinsburg is thus distinctly younger than the lower 

 part and may belong to the late Ordovician, possibly Richmond, and the break 

 may correspond in time with that found in the Mississippi Valley between the 

 Galena (Trenton) limestone and the Maquoketa (Richmond) shale. 



Read by .title in the absence of the author. 



INVERTEBRATE FAUNA OF THE GRASSY CREEK SHALE OF MISSOURI 

 BY. DARLING K. GREGER ^ 



i Abstract) 



In a paper on the formations in the vicinity of the Cap au Gres fault, pub- 

 lished by Keyes, in the Transactions of the Iowa Academy of Science, 1897, 

 page 12, the Grassy Creek shale is described in the following manner : "Imme- 

 diately beneath the well defined Louisiana limestone, in the vicinity of the 

 town of Louisiana, there are about six feet of black and green shales carrying 

 a characteristically Devonian fish fauna. Ten miles west, on Grassy Creek, 

 these shales attain a thickness of 30 feet, but southward they thin out com- 

 pletely before the limits of Pike County are reached." 



North of the region of the type locality outcrops of the formation are found 

 in Ralls and Marion counties and the maximum thickness is probably far in 

 excess of the figure given by Keyes. 



The vertebrate fauna has been described by Branson, in a bulletin of the 

 University of Missouri, and the invertebrate species of the association are de- 

 scribed in the present paper. The fauna, as I have elaborated it, is one quite 

 characteristic of the type of sediment, consisting in the main of inarticulate 

 brachiopods. Without attempting to draw any definite deductions as to the 

 age of the formation from the evidence offered by the fauna, as I have worked 

 it out, I give the following list of species : 



Ptychostylus suhtumidus Gurley. Lingula conklini sp. nov. 



Lingula missouriensis Rowley. Athyris hransoni sp. nov. 



Lingula pikensis sp. nov. Adolfla cf. umarus Swallow. 



Lingula tantilla, sp. nov. Douvillina cf. mucronata Conrad. 



Lingula rowleyiana sp. nov. Palaonilo compressa sp. nov. 



Lingula insolata sp. nov. Ptcrochwnia, longwclli sp. nov. 

 Lingula yatsui sp. nov. 



liead by title in tlie absence of the author. 



1 Introduced by E. B. Branson. 



