2 2 LOWER PENINSULA. 



FAVOSITES NIAGARENSIS, Hall. 



Tubes about one and a half millimeter wide, of equal size in 

 the same specimens, polygonal. Diaphragms flat, placed at vari- 

 ous distances, sometimes very close, sometimes more than one 

 tube diameter apart. Inner surface of tubes delicately spinulose. 

 Spinules in irregularly dispersed position. Pores situated in close 

 proximity to the angles of the tubes, not very numerous. 



External growth in convex masses, with an epithecal crust on the 

 lower side. Occurs associated with Fav. favosus in the Niagara 

 group of Michigan, Iowa, Kentucky, etc. It differs from that 

 species principally in the position of the pores near the angles, and 

 in the small tube size ; is not connecting with the specimens, Fig. 

 2, on the same plate, by gradation, an obvious break existing be- 

 tween them. 



Plate V. — Fig. i is a silicified specimen from Point Detour. 



FAVOSITES HISPIDUS, Nov. Spec. 



Tubes a little over one millimeter and a half wide, equal, poly- 

 gonal, radiated by long projecting spinules, almost reaching to the 

 centre. Spinules disposed in irregular longitudinal rows, unequal 

 in size, and more than twelve in number in the circumference of a 

 tube. Diaphragms flat, closely set. Pores very numerous, generally 

 forming two rows on each side. Of convex, discoidal growth, with 

 an epitheca below, as in the other forms. Occurs associated with the 

 preceding species in the Niagara group of Drummond's Island and 

 Point Detour. 



Plate V. — Fig. 4 is a silicified fragment found at Point Detour. 



FAVOSITES VENUSTUS, Hall. 



Synon., AsTROCERiUM venustum, Hall. 

 FAVOSITES Hl^lNGERl, Milne-Edwards. 



Tubules small, not over one millimeter wide, rounded-polygonal, 

 of equal size. Tubes radiated by long spinules, as in the former 

 species. Spinules in twelve distinct longitudinal rows. Diaphragms 



