GUELPH FAUNA IN THE STATE OF NEW YORK 25 



abundant in the dark crystalline limestone directly underlying the upper 

 Guelph chert nodules. 



DIPLOPHTT1ICM Hall. I 852 



Diplophyllum caespitosum Hall 



Diplophyllum caespitosum Hall, Paleontology of New York. 1852. 2:115, 

 pi. 33, fig. ia-r 



Cyathophyllum pelagicum Billings, Geol. Sur. Canada. Paleozoic Fossils. 

 1862. 1:108; Catalogue of the Silurian Fossils of Anticosti. 1866. p. 34 



Diphyphyllum caespitosum Nicholson, Paleontology of the Province of 

 Ontario. 1875. P- 59 



Diphyphyllum caespitosum Lambe, Ottawa Naturalist. 1899. 12:240 



Diphyphyllum caespitosum, Geol. Sur. Canada. Contrib. Canadian Paleon- 

 tology. 1901. v. 4, pt 2, p. 158 



Several fragments of coral stocks from Rochester show aggregate 

 simple, cylindric coralla of somewhat varying diameter. Most of these 

 coralla are so weathered or dolomitized that the interior structure is lost ; 

 one stock which was better preserved, afforded sections showing that 

 the coral has the internal structure described by Hall for the Niagaran 

 species D. caespitosum, viz a deep calyx ; below this an internal zone 

 with tabulae and septa, and a wide marginal zone with septa and numerous 

 dissepiments, which give this zone a cellular appearance. In mode of 

 growth also this form agrees with D. caespitosum. It is not common 

 in the chert nodules of the Guelph horizon. 



Observations. The generic relations of this species have been vari- 

 ously interpreted by different writers. Hall erected for it the genus 

 Diplophyllum, citing as differentials the characters of the distinctly sepa- 

 rated central and marginal areas of the cell, and mentioned its apparent 

 relationship to Diphyphyllum Lonsdale, without stating the differences 

 between the two. Latterly, Diplophyllum has been considered a synonym 

 of Diphyphyllum ; and Rominger, 1 who has been followed by Lambe, united 

 under Diphyphyllum both Eridophyllum and Diplophyllum, because of 



x Geol. Sur. Michigan. 1876. 3: 120. 



