Lower Helderberg Bryozoa and Corals. 113 



The conical form of the specimens, and the inequality of the cells, 

 distin Ornish this species from every other known Favosites. The speci- 

 mens are usually from one inch to nearly three inches in diameter. 



F'orinatlon a?id Joralify. — In the shaly limestone of the Lower 

 Helderberg grouj), near Clarksville, Albany county, New York. 



Favosites? minima n. sp. 



Coral forming globose or compressed globose bodies, composed of 

 minute radiating cells, about two-hundredths of an inch in diameter; 

 having comparatively thicks walls which are perforated at regular 

 distances by large pores, distant from each other less than the diame- 

 ter of the tube, a single series on each face of the tube. Transverse 

 plates rather closely arranged. 



From the globular form of this small species and where the exter- 

 nal characters are obscured by shale, it may be mistaken for the spe- 

 cies of Astylospongia found in the same rocks. From the extreme 

 tenuity of the tubes it presents the appearance of Chsetetes, but par- 

 tially decomposed specimens from Catskill creek show very beautifully 

 the casts of the intercellular pores connecting the different tubes. 

 The original cells were probably formed upon some foreign substance, 

 but from their rapid growth and curvature the}^ soon close around 

 and form spherical bodies generally a little distorted. Specimens 

 an inch and a half or less in diameter. 



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

 Helderberg group, near Clarksville, Albany county ; and Catskill 

 creek, Greene county, New York. 



Genus MICHELINA Be Koninck. 



MiCHELINA LENTICULARIS U. Sp, 



Coral forming small lenticular bodies, the lower surface the less 

 convex, and covered with a strongly wrinkled epitheca ; cells large 

 and few, broadly campanulate, with narrow partition walls strongly 

 marked by granulose or denticulate longitudinal strife, the number 

 varying with the size of the cell. 



In a specimen of little more than three-fourths of an inch in diam- 

 eter, there are about twelve cells, the larger ones somewhat more 

 than three-tenths of an inch in diameter : the whole height of the 

 specimen is about the same. 



This is a very small species, seldom attaining a diameter of more 

 than one inch. This character, with the large cells and their strongly 

 granulose striai, are distinctive features. 



8 



