10 AMERICAN FOSSIL BRYOZOA. [bull. 173. 



genera, even doubtfully, we have left the species where placed by their 

 authors, but have followed the generic name with two interrogation 

 points (??). 



We have deemed it best to be conservative in the matter of reducing 

 to synonyms, and only where the author himself or some very good 

 authority or our own investigation has justified such a course have we 

 relegated a species to synonymy. At the same time we feel sure that 

 future studies will show that a considerable number of species given 

 in our catalogue as valid are synonyms of species previously described. 

 This is especially the case with the bryozoa of the Hamilton group. 

 These have been dealt with by a number of workers, most of whom 

 have seemed to not concern themselves very much about what others 

 may have been doing. 



Some genera which future research may prove to be bryozoan we 

 have excluded. Such are Aulopora, Monilopora, Vermipora, Stri- 

 atopora, Michelinia, Cha?tetes, Favosites, and Tetradium. 



The catalogue gives a list, complete so far as we know, of the 

 described species of bryozoa from American Paleozoic formations, 

 arranged alphabetically under their genera, which are also arranged 

 alphabetically for convenient reference. The bibliography of each 

 species is given under its caption, thus enabling the student to easily 

 trace the history of any particular form in the literature. The cita- 

 tions under the genus nearly always refer to a diagnosis; it has seemed 

 to be of no value to record citations which do not contain some sub- 

 stantial contribution to the knowledge of the genus. 



We have not been able to deal with American Mesozoic and Tertiary 

 bryozoa in the same manner. Practically nothing has been done with 

 these since the work of Gabb and Horn in 1862. But not much can 

 be done yet, for the classification below the higher groups of recent and 

 post-Paleozoic bryozoa is in a most chaotic condition. This systemati- 

 zation must l)e done by European writers, as America has but a com- 

 paratively feeble representation of post-Paleozoic bryozoa. The subject 

 is difficult, but the researches of Smitt, Hincks, Jullien, and especially 

 Waters, are laying a sure foundation upon which the classification of 

 the future may be safel}^ builded. As the best that can be done at 

 present, we have given a list of all publications describing American 

 Mesozoic and Tertiary bryozoa, with the species described in each. 



As additional helps to the study of the bryozoa we have given a brief 

 outline of the Classification, with terminology and diagnoses of genera, 

 families, and suborders; tables showing the distribution of genera and 

 species geologically; and various notes and hints that we deemed might 

 prove acceptable to the student. 



One feature we have added which seems a little foreign to our pur- 

 pose, but we believe it will be appreciated. It is a list of publications, 

 as complete as we have been able to make it, treating of bryozoa. 



