Hamilton Group. 



181 



owing to the sinuous branches, frequently presents a twisted appear- 

 ance; the ridge is granulose, giving a serrated aspect. 



Locality — Hamburg, New York. 



Trematopora. subquadrata, n. sp. 

 Ramose, solid ; branches infrequent, diameter 1 mm. ; cells tubu- 

 lar; apertures oval; length .33 mm., arranged in longitudinal and in 

 oblique rows, the latter arrangement the most prominent ; occasion- 

 ally irregularly disposed; intermediate space elevated, quadrangular 

 or polygonal, minutely striated ; at each angle is a comparatively 

 strong node. 



Locality — Darien, New York. 



Trematopora PERSPiJ^ULAtA, n, sp. 

 Ramose, solid ; branches infrequent ; diameter 3 mm.: cells tubu- 

 lar, apparently angular, contiguous ; apertures varying from elongate- 

 oval to nearly circular, some having a length of .35 and a width of 

 .16 mm. ; others are circular; diameter .30 mm., irregularly and very 

 closely disposed, without elevated margin ; space between flat or little 

 elevated, with a sligl\t carina, or granulose, with numerous irregularly 

 disposed conical nodes or spines, forming the most prominent feature 

 of the surface. 



Locality — York, New York. 



Trematopora clatiformis, n. sp. 

 Consisting of an erect frond 10 mm. in height, attached by a root ; 

 branching dichotomously ; near the base the stem is round ; diameter 

 .75 mm. ; the branches become flattened and widened to 2.25 mm., 

 giving to the frond a clavate appearance. Cell-apertures polygonal, 

 contiguous, somewhat longer than wide ; length .33 mm., arranged in 

 oblique rows, at an angle of forty-five degrees to the branch ; cell 

 walls thin ; at the angles of the summit are minute spines. 



Locality — Bellona, Yates county, N. Y. 



Trematopora orbipora, n. sp. 

 Ramose, solid ; branches infrequent ; diameter 2 mm. : cells tubu- 

 lar, cylindrical ; apertures usually oval or circular, and sometimes 

 subangular from mutual pressure, diameter .40 mm., closely and regu- 

 ularly or irregularly disposed ; the more or less oblique rows seem to 

 be the most frequent arrangement of the apertures ; both margin and 



