BRYOZOA. 507 



semi-circular spaces. Apertures sub-circular or transversely 

 ovate, irregularly arranged, about 0.15 mm. in diameter, seven 

 or eight in three mm. Peristome well marked but slightly un- 

 equal being most elevated on the lower inner side. In tangen- 

 tial sections the zooecia are depressed pyriform in shape, the 

 lunarium being well developed. Interspaces quite solid near the 

 surface, but with vesicular of comparatively large size in the 

 central part of the branch. 



The small size of its branches distinguishes this species from 

 all previously described. I am indebted to Mr. J. M. Nickles, 

 of Sparta, 111., for the type specimens, which he washed from 

 the shales near his home. By this method he has brought to 

 light many very interesting species, which on account of their 

 diminutive proportions are easily overlooked when searched for 

 in the ordinary way. 



Position and locality: Lower Coal Measures, Sparta, 111. 



SCALARIPORA Hall, 1881. 



(Bry. Up. Held. p. 17.) 

 (For generic diagnosis see page 387.) 



r 



SCALARIPORA SEPARATA UMch. 

 PL XLIII, fig. 2. 



Zoarium consisting of triangular equilateral stems, each face 

 having a width of about three mm. Margins sharp, nearly 

 straight and parallel. Transverse ridges nearly as far apart as 

 the width of the faces, eleven or twelve in three cm. Portions 

 of face between margins and ridges depressed, celluliferous. 

 Apertures about 0.18 mm. in diameter and less than their own 

 diameter apart; with a faintly elevated peristome; arranged in 

 more or less regular diagonal rows, nine or ten in three mm. 

 Internal structure not observed. 



The material at hand is insufficient to determine fully all the 

 characters, but I do not think that collectors will find much 

 difficulty in identifying the species. In this genus the distance 

 between the transverse ridges is a constant character, and serves 

 very well in distinguishing the species. They are separated by 



