290 PALEONTOLOGY OF ILLINOIS. 



into their proper divisions. In the chapters on general struc- 

 ture and classification some notes on methods of investigation 

 may prove of interest and, perhaps, of value. 



An abridged bibliographical sketch, as well as a chapter on 

 comparisons between Palaeozoic and more recent Bryozoa, has 

 been prepared, but on account of a lack of space they could not 

 be printed in this volume. 



TERMINOLOGY. 



ZOARIUM (=polyzoarium and ccenoecium auctt.): The compo- 

 site structure formed by repeated gemmation. 



ZotEciuM (= cell auctt.): The true cell or chamber in which 

 the polypide is lodged. 



MESOPORES (= interstitial cells auctt.): The angular or irregu- 

 lar cells which occupy the spaces between the zocecia in many 

 of the TREPOSTOMATA and some of the CRYPTOSTOMATA. 



VESICULAR TISSUE: The vesicles which occupy the space between 

 the zocecia in the FISTULIPORID.E and other Palaeozoic Bryozoa. 



ACANTHOPORES (= spimform coralHtes Nicholson, spinifonn 

 tubuli Ulrich, Wandrohrchen Dybowski): The tubular spines 

 which are found in so many Palaeozoic Bryozoa, notably De- 

 kayia, Leioclema and Rhombopora. 



MEDIAN TUBULI (= Wandstrlingn Dybowski): Very slender 

 tubes which are present between the zocecial walls and the 

 median laminae of certain double leaved forms (e. g. STICTOPO- 

 RID^E). Their apertures at the surface are slightly elevated and 

 present the appearance of series of minute granules. The small 

 granules in Rhombopora, Stenopora and other genera, are sup- 

 posed to be of the same character. 



COMMUNICATION PORES: Small pores which pass through the 

 walls of the zooecia and establish communication between adja- 

 cent cells. 



O(ECIUM (= ovicell, gonocyst, goncecium auctt.): A modified 

 zoGeeium set apart for reproductive functions, the inflation of 



