ulrich-bassler] revision of paleozoic bryozoa 257 



As to the new species, they are to be numbered by the hundreds. 

 This is indicated by the junior author's recent paper on Homotrypa,^ 

 in which the number of the Cincinnatian species of the genus 

 previously described is more than trebled. While the specific 

 representation of this genus of the Trepostomata is exceptional, it 

 is still true that many of the other genera are very prolific in species 

 and will continue to afford subjects for papers on new forms for 

 years to come. 



This and the following papers of this series are based almost 

 entirely on the collection in the U. S. National Museum, which con- 

 sists mainly of the recently-acquired Ulrich collection. This latter 

 collection probably contains the largest series of Paleozoic bryozoa 

 extant and is the result of thirty years of work on the part of Mr. 

 Ulrich, with the assistance, at different times, of Mr. Charles 

 Schuchert and the junior author. The Museum Paleozoic series 

 has been augmented in the last few months by the collection of 

 fossils made by Dr. Carl Rominger of the University of Michigan. 

 In late years, large and excellent series of bryozoa have been collected 

 for the Aluseum from horizons in which the Ulrich collection is 

 lacking. 



Dr. Frank Burns of the U. S. Geological Survey, during the 

 course of his work in the Tertiary rocks, has collected many bryozoa 

 in horizons where they were formerly supposed to be wanting. Dr. 

 T. Wayland \'aughan has also discovered many bryozoa during the 

 progress of his studies on the Tertiary corals of America. The 

 study of these Tertiary collections is under way and it is hoped in 

 the near future to publish papers on the subject. 



All of the five orders of bryozoa comprising the subclass 

 Gymnohemata are represented in the Paleozoic rocks. Both species 

 and specimens of the order Ctenostomata are usually rare. The 

 Trepostomata, Cryptostomata, and Cyclostomata are quite abundant 

 and commonly form a considerable part of the fauna. The Chilos- 

 tomata, which includes so many Cenozoic and recent species, is 

 doubtfully recognized in the Paleozoic, the single genus Palcschara 

 probably belonging to this order. 



We deem it only right to introduce here an explanation concern- 

 ing the bryozoan chapter in the American edition of Zittel's Text- 

 hook of Paleontology. Several authors have alluded to the fact 

 that the same genera occur both among the bryozoa and the corals. 

 The explanation is very simple. 



The coral chapter had been translated without revision and 



^ Proc. U. S. National Museum, xxvi, 1903, pp. 565-591. 



