T allot — New York Helderbergian Crinoids. 17 



Art. IV. — Revision of the New York Helderbergian 

 Crinoids ;* by Mignon Talbot. (With Plates I-IV.) 



This paper treats of the Crinoidea of the Helderbergian rocks 

 of New York, and is a continuation of Dr. George H. G-irty's 

 thesis, "A Revision of the Sponges and Coelenterates of the 

 Lower ITelderberg Group of New York." In Dr. Girty's 

 paper, the term " Lower Helderberg " included the Tentaculite, 

 or Manlius, limestone; but here ''Helderbergian," as proposed 

 by Clarke and Schuchert, f is used to include only the Coey- 

 mans, or Lower Pentamerus ; the New Scotland, or Delthyris 

 Shaly ; and the Becraft, or Upper Pentamerus. 



With the exception of the work done by Wachsmuth and 

 Springer, who probably used specimens that Hall had studied, 

 the crinoids of the Helderbergian rocks of New York have 

 not received much attention since Hall's descriptions were 

 published, in 1859. Very little subsequent collecting has been 

 done, and for the most part the forms secured have been speci- 

 mens of Ilomocrinus scoparius and Edrioorinus pocilliformis 

 or simply stem fragments, the work of gathering being done in 

 the New Scotland. 



A reopening of the old locality at Jerusalem Hill was made, 

 however, in 1901, by Professors Beecher and Schuchert ; and 

 a new locality was discovered at North Litchfield, both of these 

 being in the Coeymans limestone. The majority of fossils 

 found were crinoids, but there were also cystids in appreciable 

 numbers and five ophiuroids representing two genera. In the 

 fall of 1903, these collections were increased by more material 

 collected at the same locality by Mr. C. J. Sarle ; so that in the 

 Yale University Museum there are now three collections — one 

 from Jerusalem Hill and two from North Litchfield. 



The first of these consists mainly of Homocrinus scoparius, 

 though it contains uncompressed forms of (Jordylocrinus 

 jplumosus and several good specimens of Melocrinus pachydac- 

 tylas. In the region of Litchfield, the Coeymans limestone 

 attains a thickness of one hundred and fifty feet and Homo- 



* This paper is part of a thesis presented to the Graduate Faculty of Yale 

 University for the degree of Doctor of Philosophy, in June, 1904. The 

 larger part of the work was done under the supervision of the late Professor 

 Charles Emerson Beecher, for whose help and inspiration the writer wishes 

 to make the most grateful acknowledgment. Type specimens have been 

 studied in the Yale University Museum, the New York State Museum and 

 the American Museum of Natural History : and the thanks of the writer are 

 here expressed to Professor R. P. Whitfield, Dr. J. M. Clarke, Dr. E. O. 

 Hovey and Mr. H. H. Hindshaw, for courtesies in connection with the 

 study, and to Professor Charles Schuchert, who took up the direction of the 

 work after Professor Beecher's death. 



f Science, New Series, vol. x, p. 876, 1899. 



Am. Jour. Sci. — Fourth Series, Vol. XX, No. 115.— July, 1905. 



