38 NEW YORK STATE MUSEUM 



Clathrodictyon (Stromatopora) ostiolatum Nicholson, Monogr. British 



Stromatoporidae. 1886. pt i, p. 14 

 Clathrodictyon ostiolatum Nicholson, An. and Mag. Nat. Hist. 1887. 



ser. 5. 19:11, pi. 3, fig. 1-3 

 Clathrodictyon ost i olat u m Whiteaves, Paleozoic Fossils. 1895. v. 3, pt 2, 



P- 5 2 



The great majority of the stromatoporoid bodies found in the dolo- 

 mite of Rochester and in the upper Shelby horizon are small, often incrust- 

 ing nodular masses with very fine and close lamination, a smooth or finely 

 granulate surface and conic oscula, the latter a characteristic feature of 

 Clathrodictyum ostiolatum. In the specimens under observation 

 they are however not arranged distinctly, as described by Nicholson. 

 Where the specimens are weathered, they display the characteristic nipple- 

 shaped prominences of botryoidal appearance. Thin sections show that 

 the specimens belong to the genus Clathrodictyum as denned by Nicholson 

 and Murie, specially clear being the succession of calcareous laminae with 

 intermediate vertical props or dissepiments, which do not penetrate the 

 laminae, and the " marked off cellular compartments." 



This species has hitherto been recognized only in the Guelph of Ontario. 



A section presenting the same structure was observed among the 

 museum collection of slides from a specimen ticketed as coming from the 

 Coralline limestone at Schoharie. This section also displays distinctly 

 " the internal cylindrical masses, each composed of laminae concentric with 

 a long axis," observed by Nicholson in C. ostiolatum, as the internal 

 continuation of the conic oscula. It seems, therefore, that this species is 

 common to both the Guelph and the Coralline (Cobleskill) limestone. 



BB.ACHIOPODA 



CBANIA Retz. 1781 

 Crania (sp.) 



Plate 4, fig. 6 



An imperfect upper valve with subcentral beak and squamose con- 

 centric striae has been obtained in the white chert at Rochester but is not 

 specifically identifiable. 



