I 



ON CRETACEOUS POLYZOA. 303 



evident that Dr. Marsson's attention has been, to a large extent, concen- 

 trated upon the Poljzoa of this Cretaceoas horizon more particularly. 

 This, however, I look upon as an advantage, because we have in this 

 work a monograph, which is well illustrated, of the Riigen Bryozoa, and 

 Dr. Marsson says that examples of the whole of the species described 

 by him are in his own cabinet.' 



There is still another paper which must not be passed over in silence. 

 In 1889 Dr. Pergens published the first part of his ' Revision des Bryo- 

 zoaires du Cretace, figures par d'Orbigny.' ^ In this work Dr. Pergens 

 accepts to some extent the divisions of Dr. Marsson, but the revision is 

 chiefly valuable to the student of Cretaceous Polyzoa on account of the 

 masterly way in which the author has dealt with the specific creations of 

 d'Orbigny, and that, too, with d'Orbigny's examples before him, the whole 

 of which are now preserved in the Paris Museum. 



II. Classification op Cretaceous Poltzoa. 



In the preceding pages I have given, as far as I was able, the status 

 of our present knowledge of British Upper- Cretaceous Polyzoa. It is 

 very evident, judging by the identifications of the several authors whose 

 authorities are quoted in the following lists, that the ' Palaaontology of 

 France,' vol. v., is to a large extent the real source of their information 

 on Cretaceous Polyzoa generally. Long before d'Orbigny favoured us 

 with the productions of his facile pen, Dr. Mantell (' Medals of Creation,' 

 1844) and Mr. W. Lonsdale gave some fairly faithful delineations of 

 British Polyzoa (Dixon's ' Geology of Sussex,' 1850). 



The classification originally formulated by d'Orbigny was so framed 

 as to include recent as well as fossil species, but it is evident, judging 

 from the later work of the author, that d'Orbigny himself felt that this 

 task was a difficult one. Nevertheless, we owe to this effort on his part 

 the very full and valuable synopses and lists which have already been 

 referred to. It is impossible, therefore, to accept the classification of 

 d'Orbigny as a classification ; but if we cast about for one less elaborate, I 

 am not sure that we shall meet with any that may be considered entirely 

 faultless. The classifications of Mr. Hincks or Mr. Busk, modified by the 

 researches and descriptions of Mr. A. W. Waters, must, for the present at 

 least, serve the purposes of this report. Further on I have given my 

 reasons for adopting some of the generic and specific names of d'Orbigny 

 in preference to the more modern ones when arranging the Cheilostomata. 

 In the arrangement of the Cyclostomata I have followed, though not 

 slavishly, the generic and specific distinctions of Dr. Pergens, which were 

 tabulated on pp. 279, 280 of my former report, 1890. 



III. The Chatham Chalk and its Polyzoan Fauna. 



Professor Prestwich (' Geology,' vol. ii., p. 297), with characteristic 

 brevity, refers to the zonal divisions of the Chalk ' which have of late 

 years been worked out in considerable detail, and are found to coincide 

 very closely with those previously established for the Chalk of the north 



' Since this was written I have heard of Dr. Marsson's death. Probably the 

 Polyzoa collected by him will be preserved in one of the German museums. 

 ' Bxill. de la Soc. Beige de Gcol. et Palioiitologie, tome iv. 



