A UTHOH'S PREFACE. 
Since the first volume of this Catalogue was published in 
1899, extensive additions have been made to the collection 
of Cretaceous Bryozoa, notably from the Chalk of E/iigen ; 
but circumstances have unfortunately prevented detailed 
references to much of this new material. The specimens 
accpiired since 1900 have only been examined and described 
so far as they add previously unrepresented species of 
systematic importance. With a few special exceptions, only 
species and records earlier than the }'ear 1900 are treated 
in detail. 
The attempt to include all the described Cretaceous 
genera and species has involved the difficulty of placing 
the numerous genera founded by Hamm. Doubts have 
been expressed as to their value, but the descriptions are 
usually sufficient for their recognition, and there seems no 
adequate reason for their dismissal unnoticed. Several of 
his genera fill definite systematic gaps, and it is hoped that 
reference to them will stimulate search for further material 
from the rich Bryozoan limestones of Limburg. 
During the preparation of the present volume of this 
Catalogue I have been indebted to Mr. Canu for information 
as to the horizons of the French localities; to Dr. A. W. 
Rowe for the loan of specimens and for information as to the 
distribution of Chalk species ; to Mr. C. D. Sherborn for 
frequent bibliographic help and for his determination of the 
dates of the parts of d’Orbigny’s volume on the Cretaceous 
Bryozoa and of Michelin’s Iconographie Zoophytologique,” 
a research which renders necessary some alterations in the 
