220 ME. J. W. GEEGOET ON THE 



" F. E. Edwards Collection," including Lonsdale's types. Busk's types and many other 

 specimens were obtained with the " Wetherell Collection," while additions from the 

 London Clay of Fareham and Sheppey were made by the acquisition of the collections 

 of Mr. G. E. Vine and Mr. A. Bell. 



The present paper therefore consists mainly of a description of the British Museum 

 Collection, and for permission to undertake this I have to thank Dr. H. AVoodward, 

 F.R.S. I have of course examined all other available material, including that in 

 the Reed Collection at York, at the Woodwardian Museum, Cambridge, and in the 

 Museum of Practical Geology. I must also thank Mr. E. H. M. Platnauer and Mr. E. 

 T. Newton for valuable assistance when examining the collections under their care ; 

 and I am especially indebted to Mr. H. Woods for the kind loan of the Cambridge 

 specimens. 



Furthermore I must express my best thanks to my colleague Mr. E. Kirkpatrick, of 

 the Zooloo-ical Department, for his ever-ready assistance ; owing to his kindness, I have 

 enioyed every opportunity for the examination of the collections of recent Bryozoa, and 

 especially the type specimens, to which constant reference has been necessary; he has 

 also repeatedly discussed the difficulties that have been met with, and his knowledge 

 of the recent Bryozoa and their literature has always been placed most generously at 



my service. 



II. Terminology. 



Most of the terms employed have a well-established meaning, and consequently do 

 not require to be here referred to ; but the apertures and pores of the Cheilostomata 

 are so important in diagnosis, and have been so differently employed therein, that it 

 seems advisable to define them. At the same time a few alterations in terminology are 

 suggested, as it is hoped thereby to secure greater precision in the description of the 

 fauna. 



Orifice. The opening of the mouth o£ the polypide : it corresponds iu size and shape to the 



operculum. In fossil Membraniporidse, &c., it cannot be determined. 

 Aperture. The opening occupied by the membranous area which surrounds the orifice. The 

 aperture may be primary and either correspond to the orifice as iu Lepralia or may be a 

 large space in the middle of which the orifice opened, as in Membranipiora. Or it may be 

 secondarij, formed by the peristome rising up into a tube and concealing the original primary 

 aperture ; the form of the latter may, however, be always told from the operculum. 

 ^inus. A notch on the lower side of the aperture, as iu Schizoporella. 



'JVypa. A pore which perforates the front wall of the zooecium ; it occurs ouly in the Micro- 

 porellidte : it is generally assumed to correspond to the sinus. 



Otlier names have been previously given to this, but there seem to be valid objections to 

 them all. Jullien has called it the " fenestrula; " but this term is already iu use for the 

 interspaces in the zoarium of the Fenestellidffi. D'Orbigny included it amoug the " special 

 pores/' and as such it is often referred to, though this also includes different structures. 

 The term " zooecial pore^' is hardly definite enough ; the terms "true pore," "accessory 

 opemug" {D'Orbigny), " central pore" {Busk), are subject to the same objection. 



