INTRODUCTORY ODSERVATIOXS. 93 



VII. — A Catalogue of the Zoophytes of Northumberland and 

 Durham. By Joshua Alder, Esq. 



[Read, at tlic Anniversary Meeting of the Club, May 15, 1856.] 

 INTRODUCTORY OBSERVATIONS. 



The term " Zoophytes," as employed by different authors, has 

 been made to embrace portions of the Animal Kingdom differing 

 considerably in extent and characters. It may be necessary, 

 therefore, to state that the term is here used in the same sense 

 as by Dr. Johnston in his " History of British Zoophytes." His 

 admirable work has been taken as the standard of reference 

 throughout, and its arrangement and nomenclature have been, as 

 far as possible, adhered to. When science is in a continual state 

 of progress, however, it would be inexcusable entirely to overlook 

 what has been done by recent authors. I have considered it 

 necessary, therefore, to introduce some of the imjDrovements made 

 in the arrangement of the Polyzoa by Professor Busk, in his 

 '' Catalogue of the Marine Polyzoa of the British Museum." 

 The principal alterations that have been made are in the ge-nera 

 Lepralia and Memhranipora — genera which that gentleman has 

 studied with great care. Dr. Johnston's genera" Cellularia and 

 Flustra have also been so far broken up as to bring together, 

 under the genus Bugula, a few evidently allied species, that 

 were divided in " British Zoophytes" between the two former 

 genera; and having thus dismembered the Flnstrida^, I have 

 further adopted the genus Carhasea for the remaining species of 

 Flustra with cells on one side only. The Cellularia of Johnston, 

 containing eight species, has been distributed by Mr. Busk into 

 seven genera. So great an innovation upon my "textbook" I 

 have not ventured in the present instance to adopt; and have, 

 therefore, merely indicated these alterations in the synonymy. 



Two or three local Catalogues of Zoof)hytes, each embracing a 

 portion of the district under review, have already appeared. A 

 pretty full list of the Zoophytes of the South of Durham was 

 given by Mr. Hogg, in his " Natural History of the Vicinity of 



