608 PALEONTOLOGY OF ILLINOIS. 



THAMNISCUS DIVARICANS Ulrich. 



PI. LXII, fig. 6-Cc. 



Zoarium consisting of rather stout, remotely bifurcating 

 branches spread in a plane. The bifurcations, though terminal, 

 usually seem all to spring from one side of a primary branch, 

 giving the zoariurn the appearance of unilateral development. 

 The branches are more or less nearly parallel, and, whenever 

 they are brought into close proximity, are united to each other 

 by thin dissepiments. On the reverse they are rather strongly 

 rounded and covered with very fine longitudinal striae; on the ob- 

 verse, slightly convex, 1.0 to 1.5 mm. in width, with dentate mar- 

 gins due to the lateral projection of the marginal ranges of 

 zocecia mouths. Zocecia in from five to seven ranges. Aper- 

 tures sub-circular, about 0.1 mm. in diameter, arranged in 

 parallel elevated series curving outward and upward from the 

 center to each margin of a branch very similar to the arrange- 

 ment in certain species of Idmonea,. About eight of the V -shaped 

 series occur in the length of 5 mm. The apertures really occupy 

 the summits of ridges which increase considerably in height to- 

 ward the margins of the branches. The transverse spaces be- 

 tween the apertures are more or less depressed, but not nearly 

 so much as the spaces which separate the ridges. When per- 

 fectly preserved, all the interspaces are finely granulo-striate, 

 the striations having a longitudinal direction. 



This is an unequivocal species of Tlmmniscus, and somewhat 

 resembles the T. serialis Waagen and Pichl, from the Upper Car- 

 boniferous rocks of India. It also resembles the associated 

 Polypora? gracilis Prout, especially when the branches are 

 united by unusually numerous dissepiments, as in the example 

 represented by fig. 6b. 



Position and locality: Keokuk group, King's Mountain, Ky. 



THAMNISCUS SCULPTILIS Ulrich. 



PL LXII, fig. 8, 8b. 



Zoarium small, consisting of slender, subcylindrical branches, 

 from 0.4 to 0.8 mm. in width, which bifurcate two or three 

 times at intervals varying from 3 to 4 mm. Angle of bifurca- 



