302 ■ Report of the State Geologist. 



distribution, as he refers Metriophylldm to the Devonian and 

 Streptelasma to the Silurian age. 



Zaphrentis, Eafinesque, 1820. 



Zaphrektis Roemeri, Edwards and Haime, 1851. 



Zaphrentis Roemeriy Edwards and Haime, 1851. Mon. des Polyp. Foss. des 



Terr. Pal., p. 341. 

 Zaphrentis Roemeri, Hall, 1883. Rep. State Geologist for 1882, expl. PI. I, 



figs. 11-21. 

 Zaphrentis Roemeri, Hall, 1887. Pal. New York, vol. VI, p. 2. 

 Horizon. — Lower Pentamerus and Shaly limestone. 

 Localities. — Clarksville and Indian Ladder. 



PERFORATA. 



Family Favositid^. 



Favosites, Lamarck, 1812. 



Favosites Helderbergi^, Hall, 1874. 

 Favosites Helderbergice, Hall, 1874. Twenty-sixth Rep. New York State Mus. 



Nat. Hist., p. 111. 

 Favosites Helderhergice, Hall, 1879. Thirty-second Rep. New York State Mus. 



Nat. Hist , p. 145. 

 Favosites Helderhergice, Hall, 1883. Rep. State Geologist for 1882, expl. Pi. 



IV, figs. 1, 2; PI. V, figs. 1-3; PI. VI, figs. 1-8. 

 Favosites Helderhergice, Hall, 1887. Pal. New York, vol. VI, p. 8. 



Favosites conicus. Hall, 1874. 

 Favosites conica, Hall, 1874. Twenty-sixth Rep. New York State Mus. Nat. 



Hist., p. 112. 

 Favosites conica, Hall, 1879. Thirty-second Rep. New York State Mus. Nat. 



Hist., p. 146. 

 Favosites conicus, Hall, 1883. Rep. State Geologist for 1882, expl. PI. Ill, figs. 



4, 6-13. 

 Favosites conicus. Hall, 1887. Pal. New York, vol. VI, p. 9. 



Horizon. — Shaly limestone. 



Locahty.-- Clarksville and Indian Ladder, New York ; and Cumberland, 

 Maryland. 



A comparison of Favosites conicus and F. RelderbergicB shows 

 that these species agree in many important particulars. As 

 regards the structural peculiarities and the measurement of indi- 

 vidual corallites, the two species as described by Hall are in 



