Geneea of the North American Palaeozoic Bryozoa. 575 



tubes mentioned above; for the most part, however, it is affected 

 by large openings in the walls of the lodges, by which a free 

 communication of all the animals of a colony is established. If 

 the MoNTicuLiPoaiDJi: were Bryozoa such openings must exist, and 

 they must have been observed in some case or other, but nothing 

 of the kind has ever been detected. 



"From all this it appears that the MoNTicuLiPOEiDiE are not 

 Bryozoa, and as they show the greatest affinity to Fav{ sitidje, it 

 is very probable that they must be considered as corals and 

 placed among the Hexa.oorella." 



Family Monticuliporidae, Nicholson, emend. 



Zoaria massive, discoidal, lamellar or ramose. Cells polygonal 

 in contact their entire length, increasing by intermural gemma- 

 tion or by fissiparity. Cells tabulated and invariably with "cysti 

 phragtns " near the surface. The following genera are included 

 in this family : Homotrtpa and Monticulipora. 



HoMOTBYPA, Ulrich. 



(Jour. Cin. Soc. Nat. Hist., Yol. Y, p. 240. 1882). 



Type, Uomotrypa curvata, Ulrich. 



Zoarium ramose to subf rondescent ; cells tubular polygonal, 

 arising from an imaginary axis at the center of the frond, 

 gradually diverging till near the surface, where they turn abruptly 

 outward. The tube walls are very thin till they reach the peri- 

 pheral region, where they become thickened. The thin walled 

 portion of the cells have straight diaphragms, usually infrequent. 

 In the peripheral portion of the zoarium the cells are provided 

 with a series of cystoid diaphragms or cystiphragms, the space 

 between their flexuous inner wall and the opposite wall of the 

 cell being crossed by an equal number of straight diaphragms ; 

 mesopores wanting, but the numerous gemmae or young cells have 

 sometimes the appearance of mesopores ; surface usually with 

 maculae or monticules, the centers of which are occupied by very 

 small cells, while the cells immediately adjacent to them are 



