268 



MOLLUSCOIDEA BRYOZOA 



SUB-KINGDOM V 



or less oblique, hooded, commonly of oval shape. Mesopores abundant, often com- 

 pletely isolating the zocecia. Apertures closed by a thin calcareous sheet at maturity. 

 Abundant in Ordovician. C. distincta, Ulrich. 



Crepipora, Ulrich (Fig. 436). Encrusting, lamellate, or .massive, in one case forming 

 hollow branches. Zocecial tubes long, partitioned off by a moderate number of 

 diaphragms. Mesopores almost entirely restricted to the maculae, which are distributed 

 over the surface as minutely porous elevations or depres- 

 sions. Apertures very slightly oblique, angular, or 

 sub-pyriform. Lunarium well-defined in perfect speci- 

 mens, best shown in tangential sections. Ordovician, 

 ? Silurian. 



Anolotichia impolite,, Ulr. Lower Trenton ; Minnesota. A, Surface, 

 6/1. B, Vertical section, %. C, Tangential section, i2/ ]; showing tubes 

 of lunarium. D, Tangential section of A. ponderosa, Ulr., from the 

 Cincinnati formation at Wilmington, 111., showing numerous lunarial 

 tubes (after Ulrich). 



FIG. 438. 



Ceramophyllafrondosa, Ulr. Black 

 River Shales ; Minnesota. A, Zoar- 

 ium, 2/ 3 B, Surface of same, "/i- 

 C, Two zocecia of a tangential 

 section, 12/!. I), Right half of a 

 vertical section, l -/i (after Ulrich). 



Anolotichia, Ulrich (Fig. 437). Zoaria large, ramose, or digitate, consisting of 

 long, sub-polygonal tubes intersected by remote diaphragms. Mesopores never very 

 numerous. Lunarium slightly elevated at the surface, traversed internally by two to 

 six minute, vertical, closely tabulated tubes. Ordovician. 



Diamesopora, Hall (Coelodema, Ulrich). Hollow branches, lined internally with a 



FIG. 439. 



Diam'e'sopora 

 trentonensis, Ulr. 

 Trenton ; Minne- 

 sota. Two frag- 

 ments, 2/3, and 

 one /i. 



FlG - 44 - 



Bythotrypa laxata, Ulr. Trenton ; Minnesota. A, Surface ,14/1- R Vertical 

 section, ?/ lt C, Transverse section, u/j (after Ulrich). 



striated epitheca. Zocecia as in Ceramoporella, but with thicker walls. Ordovician 

 and Silurian. 



Ceramophylla and Chiloporella, Ulrich. Ordovician. 



Bythotrypa, Ulrich (Fig. 440). Zoaria massive or lamellate. Zooecial tubes long, 

 intersected by thin diaphragms. Lunarium large ; mesopores numerous, open at the 

 surface, forming interiorly a very loose vesicular tissue. Ordovician. 



Scenellopora, Ulrich. Zoaria simple, pedunculate ; under surface with an epitheca, 



