part 2] SriiWGOTHYHIS AND spiriferina. 103 



with the generic characters of ftyriugotliyris was published in 

 1913. l Since that time, however, various circumstances have 

 prevented its completion ; and, when I resumed the work after 

 returning to civil life, it seemed desirable to publish the results 

 already obtained, leaving certain undecided matters relating to the 

 extra-Carboniferous forms to be dealt with in a subsequent paper. 

 As it now stands, the paper includes : — 



(1) A general account of the genus Syringothyris. 



(2) A discussion of the British species of that genus and their classifica- 

 tion : the detailed consideration of the remarkable forms which occur in the 

 Waulsortian knoll-phase limestones of the Cani/nia Zone in Ireland is deferred, 

 until the return of favourable conditions renders further field-work possible. 



(3) A discussion of the generic position of w Spiriferina ' laminosa (M'Coy), 

 and of the relation between the genus represented by that species and 

 Syringothyris. 



(4) Notes on Spiriferina, and certain Carboniferous Spiriferids possessing 

 a lamellose surface-ornament. 



The material used in the course of this work was in part collected 

 by myself, but for the opportunity of examining a good deal of it 

 I am indebted to the kindness of other workers, who have either 

 lent me material of their own collecting, or have given me facilities 

 for studying specimens in their care. Among the former are the 

 late Mr. C. H. Cunnington, the late Dr. Wheelton Hind, Mr. F. 

 Dixev, Mr. J. W. Jackson, Mr. J. F. Jackson, Mr. L. B. Smythe, 

 and Mr. J. W. Tutcher. Prof. E. .7. Garwood, Prof. S. H. Rey- 

 nolds, and Principal T. P. Siblv ; the latter include Mr. H. A. 

 Allen, Prof. G. A. J. Cole and Mr. W. B. Wright (Geological 

 Survey, Dublin), Dr. F. R. Cowper Reed and Mr. H. Woods 

 (Sedgwick Museum, Cambridge), Dr. A. Smith Woodward and 

 Mr. U. B. Newton (British Museum, Natural History), and Dr. 

 R. F. Scharff (National Museum, Dublin). 



My thanks are also due to Dr. F. A. Bather for his advice upon 

 a matter of nomenclature, to Mr. S. S. Buckman for suggestions 

 relating to parts ©f the paper, to Principal T. F. Siblyfor his ever- 

 ready advice and encouragement, and to Dr. F. L. Kitehin for his 

 kindness in reading and criticizing the manuscript. 



Explanation of Certain Terms used. 



In order to avoid ambiguity and unnecessary repetition in the 

 text, the precise meaning which is attached to certain frequently 

 recurring terms is indicated in the following paragraphs : — 



I. Terms applied to External Characters. 



Cardinal area. — A more or less well-developed triangular area on each side 

 of the delthyrial fissure, distinctly marked off from the general surface of the 

 shell. A cardinal area may be present in either valve, but that in the brachial 

 valve is usually inconspicuous. In this paper ' cardinal area ' always refers 

 to that of the pedicle-valve. 



1 North [25]. (Numbers in brackets refer to papers enumerated in the 

 Bibliography, § VIII. p. 224.) 



