516 PALEONTOLOGY OF ILLINOIS. 



preservation, are serrated. The cups vary greatly in size, but 

 are approximately equal on each example. The average width 

 in the two largest specimens seen is about 12 mm., while in 

 others it is only about 9 mm. At the bottom of the cups 

 there is a more or less elongated depressed solid macula. Sim- 

 ilar narrow maculae extend up the sides of the ridge at inter- 

 vals apart of 2 mm. more or less. These maculae usually oc- 

 cupy corresponding positions on each side of the ridges, and 

 being depressed terminate before reaching their summits. The 

 serrated character of the comb of the ridge is due to this cir- 

 cumstance. The spaces between the maculae is uniformly occu- 

 pied by the zooecia apertures. These are sub-circular, about 

 0.16 mm. in diameter, and nine in 3 mm., separated by inter- 

 spaces^equal in width to their diameter. 



The upper surface of this peculiar species closely resembles 

 the varieties of G. sagenella. Yet there is an important differ- 

 ence in their respective modes of growth. In that species the 

 zoariuni is celluliferous on both sides, while in this the lower 

 surface is covered with an irregular epitheca. In other words 

 one may be said to be bifoliate, the other simple and lamellate. 

 The zoarium of G. michelinia, also attains a much greater 

 thickness than any of the other species of the genus, the great- 

 est observed being about 10 mm. 



Position and locality: Warsaw beds, Warsaw, 111., and Bar- 

 rett's Station, St. Louis Co., Mo. 



GLYPTOPORA PINNATA UMch. 



PI. LXXVIII, fig. 2. 



Of this species I have seen only the imperfect example figured. 

 Judging from this the species must have been on the order of 

 G. keyserlingi Prout, and G. megastoma Ulr. At the junction 

 of the foliar expansions the zoariuni is strong and of triangu- 

 lar form in transverse section. The zooecia apertures extend 

 uniformly over this portion, there being no non-poriferous strip. 

 The maculae are solid and regularly arranged in diagonal series, 

 and in a pinnate manner on each side of the line of junction of 

 the leaves. They are somewhat elevated, but this may be due 



