GRAPTOLITES OF NEW YORK, PART 2 



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of some authors that it is abundant in the New York rocks; in fact it is 

 one of the least common of the graptolites of our Rochester shale and all 

 the references are excerpts of Hall's original description. 1 have seen alto- 

 gether not more than half a dozen specimens, including Mall's types, and 

 have not been able to find one which would reveal the form of the thecae. 



Remarks. D. ret i forme is a remarkably stately graptolite, pos- 

 sessing wide open funnel-shaped rhabdosomes, fragmentary specimens of 

 which with a diameter of no less than half a meter have been observed ; 

 and the size of the branches and the meshwork are coarse in proportion. 

 Pocta has compared it to the Bohemian D. grande Barr., also a Siluric 

 form and pointed out the differences between the two. 



Gurley remarks that " Hall's enlargements [1852, pi. 40 F] are taken 

 from an entirely different species (either D. expansum or C. sub ret i- 

 f o r m e)," but since in the earlier time all enlargements were free-hand draw- 

 ing's and often more diagrammatic than accurate, we believe that these 

 enlargements are actually taken from D. retiforme, and add here a 

 camera enlargement of our own to give a more correct conception of the 

 details of this species. 



Dictyonema gracile Hall 



Plate 1, figure 5 



Gorgonia ? Hall. Geol. N. Y. 4th Dist. 1843. p. 115, fig. 42 (right hand figure) 

 Dictyonema gracile Hall. Pal. N. Y. 1852. 2: 175, pi. .40, fig. ia-id 

 Dictyonema gracile Rominger. Geol. Sur. Mich. 1873. v. 1, pt 3, p. 44 

 Dictyonema gracile Lesquereux. Geol. Sur. Ind. 13th Rep't. 1883. p. 30 

 Dictyonema gracile Pocta. Syst. Sil. Boheme. 1894. v. 8, t. 1, p. 193 

 Dictyonema gracile Gurley. Jour. Geol. 1896. 4:308 



Dr Gurley gives the following careful redescription of this species after 

 its two type specimens in the American Museum of Natural History in 

 New York city. 



Branches about 27 (25-30) in 25 mm, only moderately diverging, very 

 straight, (hardly at all flexuous), bifurcating at intervals of 10 to 20 mm, 

 with rounded angles; very uniformly 0.4 mm in diameter, subparallel. Dis- 

 sepiments exceedingly delicate, and apparently unusually remote (2 to 3 or 

 4 mm), but in some places intermediate ones can be detected at intervals of 



