150 Thirty-second Report on the State Museum. 



TREMATOPORA, Hall. 



Trematopora] (Ch^tetes) densa. 



(PLATE X, FIGS. 11-13.) 



Trematopora densa, Hall. Twenty-sixth Report N. Y. State Mns. Nat. Hist. y 



p. 105. 1874. 



Bryozoum ramose, solid ; diameter of larger branches three mm. ; cell-tubes 

 polygonal, arising from the centre of the branch, and gradually curving to the 

 surface ; diameter of apertures variable, but averaging about .35 mm. surface, 

 with occasional maculae where the cells are larger, being about .50 mm. On 

 well-preserved specimens the angles are frequently spinose ; septa few and only 

 occurring near the surface. 



Formation and localities. In the shaly limestone of the Lower Helderberg 

 group, at Catskfll creek and near Clarksville, N. Y. 



Trematopora [?] constricta. 



(PLATE X, PIGS. 14-19.) 



Trematopora constricta, Hall. Twenty-sixth Report N. Y. State Mus. Nat. Hist., 



p. 104. 1874. 



Bryozoum ramose, hollow, frequently branching ; branches from two to four 

 mm. in diameter ; thickness of bryozoum about .35 mm. ; cell-tubes oval ; aper- 

 tures closely arranged in more or less regular, quincunx order, opening obliquely 

 upward ; margin of upper part of aperture not elevated, of posterior part strongly 

 elevated, extending over the lower portion and forming a projecting lip. There 

 are frequent maculae where the cells are larger than in other places, one of them 

 being equal in size to two ordinary cells, and frequently radiating ; inner sur- 

 face of the branch (epitheca) strongly wrinkled transversely, and longitudinally 

 striated by the recumbent position of the cell-tubes. 



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

 Trematopora dispersa, n. sp. 



(PLATE X, FIGS. 20,21.) 



Bryozoum ramose ; branches hollow ; diameter about three mm. ; cell-aper- 

 tures circular, or slightly oval ; about .30 mm. in diameter ; very irregularly 

 arranged ; in some parts contiguous, and in other parts there are large spaces 

 destitute of cells ; margins of apertures very distinctly elevated. 



This species differs from T. constricta in the cells being much less oblique, 

 and much more irregularly arranged. 



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



