POLYZOANS. 21 



The ridges on one side of the expansion correspond to 

 the central depression on the other. Zooecia apertures very 

 slightly oblique, subcircular or oval, 0.15 to 0.20 mm. in diam- 

 eter, arranged in from four to eight (usually five) alternating 

 rows between the dimples, about nine in 3 mm. Peristome 

 moderate, somewhat more elevated on one side than on the 

 other. Interspaces depressed when perfect, usually about 

 half as wide as the apertures. In thin sections the zoo3cial 

 tubes have moderately thick ring-like walls, a portion of the 

 wall being distinguishable from the rest as the lunarium by its 

 lighter color. A large number of small vesicles occupy the 

 interspaces between the zocecia walls. ( Ulrich.) 



Horizon and localities. Lower Carboniferous, Saint Louis 

 limestone : Barrett station ( Saint Louis county). 



Glyptopora sagenella (PROUT). 



Coscinium sagenella Prout, 3859 : Trans. St. Louis Acad. Sci., vol.1, p. 



573. 

 Coscinium sagenella Prout, 1866: Geol. Sur. Illinois, vol.11, p. 415, pi. 



xxii, figs. 5-5a. 

 Glyptopora sagenella Ulrich, 1890: Geol. Sur. Illinois, vol. VIII, p. 513, 



pi. Ixxviii, figs. 6-6a. 



Horizon and localities Lower Carboniferous, Keokuk 

 limestone : Bentonsport ( Iowa ) ; Warsaw ( Illinois ). 



Glyptopora megastoma ULRICH. 



Glyptopora megastoma Ulrich, 1890 : Geol. Sur. Illinois, vol. VIII, p. 518, 

 pi. Ixxviii, figs. 5-5a. 



Horizon and localities Lower Carboniferous, Keokuk 

 limestone : Keokuk and Bentonsport ( Iowa ). 



Glyptopora elegans (PRour). 



Coscinium elegans Prout, 1860 : Trans. St. Louis Acad. Sci., vol. I, p. 572. 

 Coscinium elegans Prout, 1866 : Geol. Sur. Illinois, vol. II, p. 431, pi. xxii, 



figs. 2-2*. 

 Glyptopora elegans Ulrich, 1890: Geol. Sur. Illinois, vol. VIII, p. 518, pi. 



Ixxviii, tigs. 10-lOe. 



Horizon and localities. Lower Carboniferous, Keokuk 

 limestone : Warsaw ( Illinois ). 



