486 PALEONTOLOGY OF ILLINOIS. 



greatest thickness; cross section of branches lenticular; margin 

 acute, smooth or obscurely granular. Apertures subcircular or 

 oval, with a beveled margin, slightly flaring, from 0.20 to 0.25 

 mm. in diameter, arranged in diagonal curved rows, about four 

 in 2 mm. Interspaces slightly concave, rising around the aper- 

 tures to form a kind of peristome, which is more elevated below 

 than above, causing the apertures to appear slightly oblique 

 and directed toward the distal portion of the zoarium. Lunar- 

 ium indistinct. Axial membranes very thin and somewhat flex- 

 uous. Zooecial tubes for a short distance prostrate, then curv- 

 ing abruptly they proceed to the surface at nearly a right angle. 

 Diaphragms appear to be wanting. Vesicles angular with an 

 obscure longitudinal arrangement, those along the median lam- 

 inae very large, diminishing in size and increasing in numbers 

 with age. Near the surface they are replaced by or filled with 

 calcareous tissue. 



The general appearance of this species is so much like that of 

 species of Cystodictya that I was at first inclined to refer it to 

 that genus. Upon a closer examination, however, I found that 

 the principal zooecial characters of the CYSTODICTYONHLE were 

 absent, and that in these features the species presented a marked 

 resemblance to Meekopora. Some care is required in distin- 

 guishing M. aperta from certain forms of Cystodictya pustulosa 

 Ulrich, and it will not surprise me should future investigations 

 prove these two species more closely related than is shown 

 by the material now at hand. 



Position and locality: Keokuk group. Hare at King's Moun- 

 tain, Ky. 



STROTOPORA Ulrich. 



(For generic diagnosis see page 383.) 



This genus is proposed to include a small group of Fistuli- 

 poroid species having a peculiar feature in common, which in 

 most cases is sufficiently obvious to render their separation 

 from other genera of the family a comparatively easy task. 

 The peculiarity referred to, in the ordinary state of preservation, 

 presents itself in the shape of large abruptly spreading cells, 

 having at the bottom an aperture of the average zofBcia size, 



