MR. A. W. WATEPvS ON NORTH ITALIAN BRYOZOA. 153 



14. JS'oRTH Italian Bryozoa. — Part II. Cyclostomata. By Arthur 

 Wm. Waters, Esq., F.L.S., F.G.S. (Read January 27tli, 1892.) 



[Plate III.] 



The Chilostoraata from the same localities were dealt with in 

 vol. xlvii. (1891) p. 1 of this Journal. It is always unsatisfactory 

 to describe Cyclostomata, as there are so few characters that can be 

 employed in classification, nor are we yet sure as to the relative 

 importance of those used. The difficulties are much increased by 

 the vast number of named species based upon some slight difference 

 in the mode of growth, and in some cases the individual state of 

 preservation has been the ground of a new species. 



I have before me a list of 424 names of Tertiary Cyclostomata,^ 

 which no doubt could be increased to nearly 600, but we are 

 certainly within the mark when we say that of these more than 200 

 could not be recognized again, while many are known to be only 

 synonyms. 



In the Tertiaries Hornera, Idmonea, Filisjparsa, and Entalojpliora 

 are by no means sharply-defined genera, and seem to run into one 

 another. 



The most interesting species dealt with is a new one, which I 

 have called Diastopora hrendolensis. It has a tubule to most zooecia, 

 .but diff'ers from the living species D. obelia, which also has tubules ; 

 for in the fossil they run up more by the side of the zooecium, whereas 

 in D. ohelia they are on the front of the zooecium, about the middle. 

 The zoarium is usually erect, formed by very compressed branches 

 with zooecia on both sides ; but there are, besides, some incrusting 

 specimens having similar small zooecia provided with tubules. This 

 would seem to show that those who united under Diastopora erect 

 and incrusting forms were right. The genera Mesente7npora and 

 Bidiastopora are, however, retained by some. 



The oviceU by the side of the zoarium of Hornera serrata is in a 

 position new for the Cyclostomata. 



^ A similar list of Tertiary Chilostomata comprises about 1400, and I have 

 little doubt that I could bring the list up to 2000. The number of names of 

 Cretaceous species must be as large, and the list of Palaeozoic bryozoa also very 

 considerable ; from these figures we may see, therefore, that there is an over- 

 whelmingly large field not yet reduced to order. 



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