Genera of the JSTorth American Palaeozoic Bryozoa. 591 



Trematopora, Hall. 

 (Pal. K Y., Yol. II, p. 149. 1852.) 

 Type, Trematojpora tuberculosa, Hall. 



(Plate 19, figs. 1-5.) 

 Zoarium ramose, branches solid ; surface with or without 

 monticules ; cells cylindrical, walls thin ; apertures circular or 

 oval, irregularly disposed ; peristomes equally elevated ; meso- 

 pores with numerous tabulae ; iaterapertural space solid. Fre- 

 quently spinules occur between the cell apertures or on the 

 peristomes. 



This genus in its manner of growth is very similar to Callo- 

 POBA, but differs from that genus in having a solid surface be- 

 tween the cell apertures. The solid surface is a persistent feature 

 in all the species of this genus. 



Idiotbtpa, Ulrich. 

 (Jour. Cin. Soc. E'at. Hist., Yol. YI, p. 272. 1883.) 



Type, Idiotrypa parasitica, Ulrich. 



Original diagnosis. Zoaria parasitically adhering to foreign 

 objects ; cells of two kinds, the true zooecia being subcircular, 

 with a slightly elevated thin peristome, and more or less com- 

 pletely separated from each other by a series of large angular 

 interstitial cells. The two sets of cells are not distinguishable 

 from each other in vertical sections, both being crossed by thick 

 horizontal diaphragms occurring at short and regular intervals 

 so as to divide the zoarium into so many equal layers. 



187 188 189 



^*-^'V---v*«^ 





Fig. 187. Idiotrypa parasitica. Surface xl8. 

 Fig. 188. Transverse section. xl8. 

 Fig. 189. Vertical section of same, xl8. 



