24 PALEONTOLOGY OF NEW YORK. 



length from .33 to .50 ram., width from one-half to three-fourths the length ; 

 closely unci irregularly disposed. Anterior margin thin, slightly elevated, 

 gradually growing more prominent, and at the posterior end strongly 

 elevated, oblique, denticulated, constricting that portion of the aperture. 

 Mesopores variable in size, some having a diameter of only .15 mm., while 

 others are nearly as large at the cell apertures ; margins very thin ; height 

 equal to that of the anterior margin of the cell aperture. 



I had formerly considered this species a form of Fistulipora parasitica, but its 

 apparent parsusitie character is due to the fllattening of the larger branches and 

 their atUvchnient to other bodies. 



Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 



Callotrypa, n. s. g. 



The species resemble Callopora in their general characters, but differ in 

 having a solid intercellular space, or which is sometimes occupied by minute 

 tubuli, destitute of septa ; while in that genus the intercellular space is vesicular 

 or occupied by septate tubuli. 



Callopora (Callotrypa) macropora. 



PLATE XI, FIGS. 25-29 ; AND PLATE XXUI, FIGS. 16-19. 



CaUtipora macropora. Hall. Twenty-sixth Rept. N. Y. State Mus. Nat. Hist., p. 101. 1874. 

 " Thirty-second Kept. N. Y. State Mus. Nat. Hist., p. 152. 1879. 

 In part Callvpora MOcrvpura, Hall. Report of State Geologiat for 1882. Expl. pL 11, figs. 23-29. 1883. 



ZoARiUM ramose, solid, diameter of branches from 1 to 2 mm. ; bifurcations fre- 

 quent; branches diverging from forty-five to ninety degrees. Cells tubular, 

 arising from the center of the branch and regularly curving to the surface, 

 increasing by interstitial addition ; in contact for the greater portion of their 

 length. Walls thin, becoming thicker near the surface and slightly constrict- 

 ing the cell tube. Apertures oval or polygonal from mutual pressure, length 

 on different specimens from .33 to .50 mm., width from one-half to two-thirds 

 the length ; irregularly dispo.sed, generally some portion of each aperture in 



