BRYOZOA—TREPOSTOMATA. 133 



pores) regularly disposed, and surrounded by cells somewhat 

 above the average in size. 



Utica beds of the Cincinnati region. A common fossil. 



XXXVI. Dekayia E. and H. 

 Subcylindrical or flattened stems growing from large base ; one 

 set of acanthopores and few or no mesopores and diaphragms. 

 Otherwise like preceding. Ord.-?Dev. 



56. D. aspera E. and H. (Fig. 190, c.) Ordovicic. 

 General form and aspect like Dekayella ulrichi, from which it 



differs in generic characters. 



Lorraine of the Cincinnati region. 



XXXVII. Batostomella Ulrich. 

 Slender branches, with thick-walled zcecia, few diaphragms, and 

 small circular or oval apertures with rounded or canaliculate inter- 

 spaces ; numerous small acanthopores, and mesopores, the latter 

 with subcircular openings. Sil.-Perm. . 



57. B. granulifera (Hall). Siluric. 

 Oval to elongate apertures margined by wavy, raised, granu- 



lose lines, double between cells. 



Rochester shale of New York, etc.; common. Waldron, Ind. 



58. B. spinulosa (Ulrich). (Fig. 190, d.) Mississippian. 

 Subcircular or oval apertures, surface hirsute in well preserved 



specimens, from abundance of acanthopores. 

 Chester of Kentucky and Illinois. 



XXXVIII. Bythopora Miller and Dyer. 

 Usually slender branches, zocecia practically without diaphragms, 

 and with oblique apertures, canaliculate interspaces, few meso- 

 pores and comparatively strong acanthopores, rarely more than 

 one to each zocecium. Ord.-Dev. 



59. B. delicatula (Nicholson). Ordovicic. 

 Like Bythopora spinulosa, but without the spines. 



Richmond beds of Ohio, Indiana, Ontario and Manitoba. 



60. B. herricki Ulrich. (Figs. 188, e, 190, e.) Ordovicic. 

 Similar to preceding, but with apertures long drawn out anter- 

 iorly and narrower. 



Black River of Minnesota. 



