BBYOZOA. 675 



at a right angle from the posterior wall and extend to a point 

 a little further than midway to the opposite wall. The inter- 

 vals between them about equal the diameter of a zooecium. 

 These incomplete diaphragms may also be detected in tangen- 

 tial sections. 



Prout's description and figures of his Cyclopora discoidea, leave 

 so much unsaid that I found it quite impossible to identify the 

 species with certainty. As, however, several of the specimens 

 used in drawing up the above diagnosis of the species were so 

 named by Dr. Prout himself, I feel reasonably confident that 

 they are the same as the original examples. Three outwardly 

 very similar yet very distinct species, the Cyclopora fungia 

 Prout, Cycloporella spinifera Ulr., and the present species, are 

 associated in the Keokuk limestone at Warsaw and other locali- 

 ties in the State. The difficulty of separating them is greatly 

 aggravated by the fact, that in perhaps nine cases out of ten, 

 the specimens show only the under side. Here they look de- 

 cidedly alike and it was only after considerable practice that I 

 could separate them successfully. Thin sections will, of course, 

 immediately distinguish the species, while there is also very 

 little difficulty in separating specimens showing the celluliferous 

 side. 



Position and locality: Keokuk group. Warsaw, Hamilton, 

 and Nauvoo, Illinois, and Keokuk, Iowa. 



CYCLOPORELLA Ulrich. 



(For generic diagnosis see page 404.) 



This genus is founded upon C. spinifera. Provisionally I place 

 another species here, though fully aware that it is widely differ- 

 ent from the type. 



CYCLOPORELLA SPINIFERA Ulrich. 



PI. LXIX, fig. 1-lc. 



Zoarium discoidal, thickness 1 mm. or less. Under surface 

 nearly flat, witli a small central elevated scar of attachment; 

 epitheca showing faint concentric wrinkles and radiating striae. 

 Upper surface strongly spinulose, sometimes witli smooth spots, 



