Lower Helderbero Brtozoa and Corals. 107 



surface between tlie rows of cells. Well preserved specimens from 

 Catskill creek show a short spine at the lower end of the cell aper- 

 ture ; a feature not observed in other localities. 



Formation and locality. — In the shaly limestones of the Lower 

 Helderberg group, near Clarksville, Albany county, New York. 



PALESCHAKA ISTov, Gen. 



Bryozoum parasitic, or free, forming incrustations upon the sur- 

 faces of other fossils, or in independent frondose expansions. Surface 

 with polygonal cellules, separated by thin solid walls ; without evi- 

 dence of rays or transverse septa. 



The mode of growth is not dissimilar from that of a recent Flustra 

 in its earlier stages, but the cells are less regularly arranged and the 

 whole has a stronger and firmer aspect. 



Paleschara incrustans n. sp. 

 Bryozoum growing in flustra-like expansions, incrusting shells and 

 other bodies ; sometimes more than an eighth of an inch in thick- 

 ness from additions of growth. Cell apertures moderately large, 

 polygonal ; five to seven in the space of one-tenth of an inch ; walls 

 thick, their margins elevated at the angles of the cell apertures into 

 obtuse projections, which are not sufficiently long to be characterized 

 as spines. Sometimes the surface exhibits maculae of larger cells ; 

 but this feature is obscure. 



The general expression of this Bryozoan is that of a Flustra ; the 

 the cells are very similar to some forms of Chaetetes ; but no trans- 

 verse partitions have been discovered. 



Forraat'ton and locality. — In the shaly limestones of the Lower 

 Helderberg group, near Clarksville, Albany county. New York. 



Paleschara bifoliata n. sjp. 

 Bryozoum growing in broad, spreading fronds, or thin expansions, 

 celluliferous on one or both sides, with an epithecal crust forming the 

 base of the cells. The same or similar epithecal expansions may be 

 found incrusting other substances. Surface of the frond covered 

 with small, closely arranged, slightly elevated maculae, formed of 

 larger cells, with thicker walls than those dividing the ordinary cells. 

 Cells polygonal, often slightly-elongated hexagons, in undulating or 

 tortuous lines or irregularly disposed ; cells rectangular to the plane 

 of the frond or slightly inclined ; without transverse plates, walls thin. 



