BRYOZOA. 381 



the posterior side, making the aperture appear more oblique 

 than it actually is. Lunarium scarcely distinguishable in tan- 

 gential sections. Mesopores fairly numerous, rather equally dis- 

 tributed among the zooecia. Diaphragms usually absent; occa- 

 sionally one may be observed closing the apertures. 



Type: D. dichotomy Hall. Range, Trenton to Lower Helder- 

 berg. 



CHILOPOKELLA Ulrich. Zoaria rising up into flabellate fronds 

 or compressed branches, from a greatly expanded heavy crust. 

 Zoopcial tubes long: very thin-walled, large, and of irregular 

 shape in the axial region. Walls much thickened near the sur- 

 face. Apertures ovate, the lunarium conspicuously elevated. 

 Mesopores numerous. Diaphragms few, generally absent. 



Type: C. flabellata Ulrich. Cincinnati group. 



AXOLOTICHIA n. gen. Zoaria large, irregularly ramose or 

 digitate. Zooecia comparatively large, forming long sub-poly- 

 gonal tubes, intersected by remote diaphragms. Walls thin, 

 transversely lined in vertical sections. Apertures sub-oval, di- 

 rect, with the lunarium, which occupies about two-fifths of the 

 margin, elevated. Thin sections show the lunarium to have 

 been traversed vertically by from three to six minute, closely 

 tabulated tubes. Mesopores of irregular form, moderately 

 abundant, rather equally distributed among the zooecia. 



Type: A. ponderosa Ulrich. Range, Trenton to Cincinnati. 



SPATIOPORA Ulrich. Zoaria forming thin parasitic crusts upon 

 foreign bodies, the shells of Orthoceras being the most favored. 

 Surface even or with monticules. Zoo?cia short with direct ir- 

 regular apertures. Lunarium scarcely perceptible even in thin 

 sections. Mesopores very few, usually absent. Interspaces often 

 with large blunt spines (?acanthopores). Walls of zooecia mod- 

 erately thin, with the characteristic structure pertaining to the 

 family. 



Type: S. aspera Ulrich. Range, Cincinnati group; possibly to 

 the Niagara. 



