CORALS AND BRYOZOA. 101 



This species may be distinguished from S. scalariformis by its much smaller 

 size, slight concavity of the face of the branches, and less frequent bifurcations. 

 Formation and locality. Upper Helderberg group. Falls of the Ohio river. 



THAMNOTRYPA, N. G. 



Thamnopora, Hall. 1881. 

 Not Thamnopora, Steininger. 1831. 



Thamnotbypa divakicata. 



PLATE XXXin, FIGS. 9, 10. 



Thamnopora divaricata. Hall. Trans. Albany Institute, vol. x, abstract, i>. 16. 1881. 



" " Report of State Geologrist for 1882. Expl. pi. 26, figs. 9, 10. 1883. 



ZoARiuM consisting of a main branch or stipe, from which proceed, at irregular 

 intervals, lateral branches diverging at an angle of nearly ninety degrees ; 

 width of stipe from 1 to 1.25 mm.; transverse section lenticular; greatest 

 thickness .50 mm. ; width of branches .50 mm. Cell apertures oval, length 

 .25 ram., width two-thirds the length ; on the stipe usually disposed in two 

 longitudinal rows, sometimes three, and rarely four for a short distance ; on 

 the lateral branches there are only two rows Ranges of cells separated by 

 a slight elevation. Peristomes strong, distinctly and equally elevated. 



Formation and locality. Upper Helderberg group, near Buffalo, N. Y. 

 GLAUCONOME, Goldfuss. 1826. 



GlAUCONOME 8INU0SA. 



PLATE XXXm, FIGS. 11, 13. 



Qlaueonome sinuo»a. Hall. Trans. Albany Institute, vol. x, abstract, p. 18. 1881. 



" " " Report of SUte Geologist for 1882. Expl. pi. 26, figs. 11, 12. 1883. 



Width of main stem slightly less than 1 mm., of lateral branches .50 mm. ; 

 transverse section broadly sub-cuneiform. Celluliferous face angular, oppo- 

 site face rounded. Space between lateral branches equal to the width of a 



