634 PALAEONTOLOGY OF ILLINOIS. 



and rarely nine in 1 cm. longitudinally. The zooecia form two 

 ranges on the branches, with twenty-two or twenty -three in 5 

 mm., and three irregular rows on the dissepiments. The aper- 

 tures are comparatively large, being 0.14 mm. in diameter, and 

 separated by little more than half their diameter. One of the 

 principal features of the species is the large number of the 

 accessory pores on the reverse side. A few of these pores also 

 occur among the zooecia apertures. 



Position and locality: Upper Coal Measures, Fayette County, 

 Illinois. 



SEPTOPOBA ROBUSTA var. INTERMEDIA Ulrich. 



PI. LVI, fig. 10, and PI. LXIV, figs. 4-4a. 



Under this provisional name I desire to make known a form 

 from the Chester limestone of Kentucky, that differs from the 

 typical form in having more delicate branches, and longer and 

 more arched dissepiments. The former vary in width between 

 0.4 and 0.7 mm., and the latter usually carry only two rows 

 of zooecia. There are three specimens, two from near Litchfield 

 and one from Sloan's Valley. One preserves the base with a 

 large number of rootlets. 



SEPTOPORA DELICATULA Ulrich. 



PI. LXIV, fler. 5-5a. 



Of this species only the reverse is known, but this is so char- 

 acteristic that there is no danger of mistaking the species. The 

 zoarium is small and exceedingly delicate. The branches are 

 rather narrowly rounded, distinctly striated, and vary in width 

 between 0.2 and and 0.4 mm. The intervals between them 

 average 1.2 mm. Dissepiments or connecting pinnae slender, 

 about two-thirds as wide as the branches, and 1.2 to 1.5 mm. 

 distant from each other. A few accessory pores are developed, 

 usually at the base of the dissepiments. 



Position and locality: Lower Coal Measures, Seville, Illinois. 

 Associated with Fenestella wortheni, F. sevillensis, Rhombopora 

 multipora, (Foerste) and other species. 



