THE BRYOZQA, OR MOSS ANIMALS. 



By R. S. Bassler, 

 United States National Museum. 



[With 4 plates.] 

 CONTENTS. 



Page. 



Introduction 339 



General characters 340 



Classification 342 



Collection and preparation for study 344 



Methods of study 346 



Types of Bryozoa 350 



Subclass Entoprocta 350 



Subclass Ectoprocta 351 



Superorder Phylactolaemata — 351 



Page. 

 Types of Bryozoa — Continued. 



Superorder Gymnolaemata , 353 



Order Ctenostomata 353 



Order Cyclostomata 356 



Order Trepostomata 359 



Order Cryptostomata 363 



Order Cheilostomata 364 



Distribution of the Bryozoa 375 



Stratigraphlc value 376 



INTRODUCTION. 



To the layman the paradoxical term "moss animals" has little 

 significance, and even to the scientific student this, or its Greek 

 equivalent, " Bryozoa," is often no more than a name. Yet these 

 microscopic animals, growing often into mosslike colonies, are ex-< 

 tremely abundant in the present-day seas at all latitudes, and their 

 fossil remains are equally common and widespread in almost all the 

 sedimentary rocks since early geologic times. Notwithstanding this 

 great development in both the past and the present, the study of the 

 bryozoa has always been limited to a comparatively few specialists 

 who have been unable to overcome the popular belief that this group 

 of animals presents too difficult a problem for any but the expert 

 willing to spend a lifetime of research upon them. This belief has 

 been strengthened by the fact that practically all of the published 

 works upon the bryozoa are of a highly technical nature and usually 

 deal with some special subject. In none of them is there a review in 

 relatively simple language of the class as a whole. The present article 

 has been prepared in an endeavor to remedy this condition. Descrip- 

 tions and illustrations of typical examples of the various types of 

 bryozoa, both fossil and recent, the methods employed in studying 

 them, and the interest and value of this study from various stand- 

 points are presented in the hope that the class will in future receive 

 the attention that it deserves. 



339 



