330 THE PALEONTOLOGY OF MINNESOTA. 



[Ceranioporellii interporosa. 



CEKAMOPOBELLA INTERPOROSA, n. sp. 



PLATE, XXVIII, FIG. 12. 



All the Minnesota examples seen are thin crusts upon foreign bodies, but in the 

 Cincinnati rocks the species often forms large masses by superposition of numerous 

 layers. The zocecial apertures are larger, more direct, and comparatively wider than 

 in C. distincta Ulrich, with an average of nine in 3 mm. Fig. 12 represents the 

 usual appearance of the surface. Sometimes the lunarium is better distinguished 

 from the rest of the posterior hood than shown in the figure. The mesopores are 

 always numerous and generally more equally distributed around the zooecia than in 

 other species of the genus. 



Formation and locality. In Minnesota the species has been noticed only in the Galena shales of 

 Goodhue county. At Cincinnati, Ohio, the same species apparently is not uncommon in the lower 300 

 feet of strata. 



Mus. Reg. No. 7647. 



Genus DIAMESOPORA, Hall. 



Diamesopera, HALL. 1852, Pal. N. Y., vol. ii, p. 158 (not defined); Pal. N. Y., vol. vi, p. xv, 1887: 



ULRICH, 1890, Geol. Surv. 111., vol. viii, pp, 380, 467. 

 Cceloclema, ULRICH. 1882. Jour. Cin. Soc. Nat. Hist., vol. v (not defined). 



Zoaria ramose, branches hollow, lined internally with a striated epitheca. In 

 other respects very much like Ceramoporella and Ceramophylla. 



This name stands for an easily recognized division of the Ceramoporidce. The 

 genus may be more convenient than natural, yet- 1 must confess that the evidence 

 so far gathered points rather to an opposite conclusion. The species next described 

 is the earliest known. Several occur in the Cincinnati rocks, but it is not till we 

 come to the Niagara that the genus has its greatest development, both in the way 

 of species and individuals. 



DIAMESOPORA TRENTONENSIS, n. sp. 



PLATE XXVIII, FIG. 14. 



Zoarium consisting of small hollow branches varying from 1.5 to 3.5 mm. in 

 diameter; thickness of zoarium 0.4 to 0.8 mm.; axial tube varying in diameter, the 

 epithecal lining not observed. Small maculaB sometimes present. Zooacial aper- 

 tures oval, about their diameters apart, arranged sometimes regularly in diagonally 

 intersecting rows, at other times as shown in fig. 14; averaging nine in 3 mm. 

 When regularly arranged they are set into obliquely depressed subrhomboidal areas, 



