474 PALAEONTOLOGY OF ILLINOIS. 



from an imaginary axis to the surface with a gradual curve. 

 Diaphragms thin, about two tube diameters apart. Mesopores, 

 variable in shape and of moderate size, are numerously inter- 

 spersed among the zocecia. In thin sections the lunaria present 

 a very peculiar feature. Thus, when the tube is cut transversely 

 the lunarial or narrowest side is apparently composed of alter- 

 nating intervals of light and dark color. When viewed under a 

 high power the light intervals are seen to be of circular form, 

 and with the aid of vertical sections, we learn that they are 

 really of the nature of small vertical tubes. Two of the sides 

 must have been bounded by extremely thin walls, as they are 

 only very rarely preserved, the appearance ordinarily presented 

 in tangential sections being that of a simple perforation in the 

 zooecial wall. These small tubes, of which there are usually 

 about six in each lunarium, appear to have been crossed by 

 numerous diaphragms, usually about twice their diameter apart. 



The massive ramose zoarium, and large zocecia, suffice to sep- 

 arate this species from all associated Bryozoa. 



Position and locality: Cincinnati group; very abundant at 

 Wilmington, 111. 



FISTULIPORA McCoy, 1849. 



(Ann. and Mag. Nat. Hist. ser. 2, Vol. Ill, p. 131.) 

 (For generic diagnosis see page 382.) 



It is only since December, 1885, that we know exactly what 

 form McCoy had before him when he proposed this genus. At 

 the date cited there appeared in the Ann. & Mag. of Nat. Hist, 

 a valuable treatise on the genus Fistulipora by Dr. H. A. Nich- 

 olson and Mr., A. H. Foord. The authors show that Dr. Nichol- 

 son's identification of McCoy's . F. minor* (upon which I had 

 based my estimate of the character of the genusf) was incorrect 

 the new name F. mucosa being applied to the species. It fur- 

 ther appears that McCoy's F. minor is identical with Phillip's 



* Palaeozoic Tabulate Corals, 1879. 



t Am. Pal. Bry. Jour. Cin. Soe. Nat. Hist. Vol. VII, p. 43, 1884. 



