BRYOZOA—CRYPTOSTOMATA. 



161 



LXXXIV. Dichotrypa Ulrich. 



Like Cystodictya, but in form a large, thin, bifoliate expansion, 

 with solid maculae on surface. Dev.-Miss. 



146. D. lyroides Ulrich. (Fig. 214, c.) Mississippian. 

 Frond free, lyre-shaped, with thick, solid, rounded margins ; 



surface with broad monticules, with solid circular or substellate 

 maculae, bordered by larger cells. 

 St. Louis of southern Kentucky. 



LXXXV. T^niopora Nicholson. 

 Differs from Cystodictya in having a strongly elevated, longitudinal 

 central ridge on each face, making cross-section somewhat rhom- 

 boidal. Dev. 



147. T. exigua Nicholson. (Fig. 212.) Devonic. 

 Non-celluliferous margin comparatively narrow, carinas on main 



stem and branches strong, rounded ; apertures circular, with strong 

 peristomes. 



Hamilton of Western New York and Ontario. 



148. T. penniformis Nich- 

 olson. Devonic. 

 Keel broader and more 

 strongly elevated, and non- 

 celluliferous margin wider, 

 than in the preceding; aper- 

 tures arranged in oblique 

 transverse rows; peristomes 

 pronounced. 



Hamilton of Western 

 New York and Ontario. 



Fig. 212. Tceniopora exigua. a, fragment 

 X I ; and b, small portion X 6. (After Hall 

 and Simpson. ) 



LXXXVI. Coscinium Keyserling. 

 Differs from Cystodictya in having the branches inosculating at 

 short intervals, so as to produce broad fronds, perforated at rhyth- 

 mic intervals by elliptical or circular fenestrules. Dev.-Carb. 



149. C. cribriforme Prout. Devonic. 



Cells tubular, very oblique, the apertures trilobate, or when 

 worn, arched or subtriangular, closely and irregularly disposed ', 

 fenestrules varying greatly in size and distance from each other; 

 lunarium elevated. 



Hamilton of Falls of the Ohio and Utica Ind. 



