REPORT OF THE DIRECTOR I918 20/ 



leria socialis, and that of this higher shale as that of 

 Ceratiocaris salina.^ 



The prominence of Hughmilleria in the Pittsford shale, its suppres- 

 sion in the Vernon shale and its entire absence in the Bertie water lime 

 and in still later eurypterid-faunas are significant facts in regard to 

 the age-determination of the Shawangunk grit fauna. The Sha wan- 

 gunk grit was correlated with the Pittsford shale, when its fauna was 

 discovered and found to contain as its dominant element a Hugh- 

 milleria. This conclusion was unavoidable at the time, the genus 

 Hughmilleria then not being known from any other horizon and 

 locality in this country. 



The discovery of the Ordovician eurypterid-faunas, described by 

 Clarke and Ruedemann in the Eurypterida of New York from the 

 Normanskill shale and the Schenectady beds, has thrown a different 

 light on the range of Hughmilleria, for in these Ordovician faunas 

 Hughmilleria was found to be a constant and dominant element. 



The Hughmillerias of the Pittsford shale and Shawangunk grit, 

 not being specifically identical can therefore no longer be considered 

 as demonstrating the taxonomic equivalency of these beds. The 

 Hughmillerias of the Pittsford shale, Vernon shale and Shawangunk 

 grit are clearly the last stragglers of a once flourishing race and, as 

 such, of less stratigraphic significance than they would be otherwise. 

 On the whole their occurrence in a Silurian horizon would indicate 

 an age earlier than the Bertie waterlim.e and a relative dominancyof 

 species of Hughmilleria would point to a comparatively early Silurian 

 age. 



NOTES ON THE FOSSILS OF THE VERNON SHALE 

 Hexameroceras chadwicki nov. 



Plate 3, figures 7-9 



Professor Sarle (1903, p. 1085) cited from the Pittsford shale a 

 " pentalabiate Gomphoceras." The specimen to which Professor 

 Sarle had reference is now in the State Museum and consists of a 

 living chamber with poorly preserved aperture, leaving it undecided 

 whether the form belongs to Pentameroceras or Hexameroceras (see 

 Ruedeniann, 19 16, pi. 27, fig. i). 



The Vernon shale has afforded a specimen, here figured, that in 

 size and outline agrees with the fragment from the Pittsford shale and 



^As pointed out to me by Mr Hartnagel, it is of interest to note that the 

 occurrence of this fauna is near the western terminus of the red SaHna shales. 

 This may explain the fact that the development of the Vernon at Pittsford is not 

 quite typical and also account for the presence of a higher intercalation of dark 

 fossiliferous shale. 



