436 PALEONTOLOGY OF ILLINOIS. 



BATOSTOMELLA NITIDULA Ulrich. 



PI. LXXV, flg. 3-3&. 



In this species the zoarium consists of very slender branching 

 stems, about one mm. in thickness. Surface even, hirsute. Cell 

 apertures oval, variable in size, the largest about 0.15 mm. in 

 their longer diameter; about eight in two mm., with only mod- 

 erately thick interspaces. Often the cell aperture is provided 

 with an .opercular structure having a central perforation. 

 Zocecial walls frequently flexuous in the axial region, consider- 

 ably and abruptly thickened in the cortical zone. Mesopores 

 moderately abundant. Diaphragms almost wanting. A single 

 row of acanthopores encircles each zooecium. 



This species holds an intermediate position between B. spinv- 

 losa and B. abrupta. The greater irregularity in branching, 

 the larger cell apertures, less numerous acanthopores, greater 

 obliquity of zocecial tubes in the axial region, thinner inter- 

 spaces and other points separate it from B. spinulosa. The 

 comparatively wider cortical region, thinner interspaces, fewer 

 acanthopores, and more slender habit of growth, distinguish it 

 from B. abrupta. 



Position and locality: Chester group; Chester, 111., and Sloan's 

 Valley, Ky. 



STENOPORA Lonsdale, 1845. 



(Strzelecki's Phys. Desc. N. S. Wales, p. 09.) 

 (For generic diagnosis see page 375.) 



Like the genera Chaetetes and Monticulipora this genus has 

 for many years served as the receptacle for very diversely con- 

 structed Palaeozoic Bryozoa. We owe it to the labors of Dr. H. 

 A. Nicholson and Mr. B. Ethridge, Jr., that we now possess 

 some adequate idea of the true structure of the genus, these 

 naturalists having published a short time ago critical descrip- 

 tions and figures of Lonsdale's types* together with several 

 new species. 



The present addition to our knowledge of Stenopora makes 

 it abundantly evident that the genus has no affinities with the 

 FAVOSITID^E, but that in Batostomella on the one hand, and 



* Ann. and Mag. Nat. Hist, Vol. IV. 1879, and Vol. XVII, 1886. 



