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Vr.— Oaradocian Oystidea from Girvan. By F. A. Bather, M.A., D.Sc, F.R.S. 

 Communicated hy Dr Horne, F.R.S. (With Six Plates.) [Published by per- 

 mission of the Trustees of the British Museum.] 



(Read May 13, 1912. MS. received March 8, 1913. Issued separately July 24, 1913.) 



A. Introduction 



Geological Distribution in Girvan 

 The Starfish Bed 



B. Systematic Description — 



Order Ami)horidea 



(Discussion of the " Carpoidea") 

 Suborder Heterostelea 



(Taxonomy of the Suborder) 

 Fam. Dendrocystidae . 

 (Rhipidocystidae ?) 

 Dendrocystis 



D. Barrandei n. sp. 

 D. Sedgwicki 

 D. scotica n. sp. 

 D. rossica 

 D. paradoxica 

 Fam. Cothurnocystidae 

 Cothurnocystis . 

 G. Elizae n. sp. 

 G. curvata n. sp. . 

 Organisation and Mode of Life 

 Affinities of the Genus . 

 Order Rhombifera 



(Taxonomy of the Order) . 

 Superfam. Glyptocystidea 

 Fam. Cheirocrinidae 

 Cheirocrinus 



C constrictus n. sp. 

 G. interruptus 



(The names of 



CONTENTS. 



SECTION 

 1 



4 



13 



16 



21 



26 



33 



34 



40 



89 



108 



127 



150 



155 



160 



161 



170 



208 



223 



245 



261 



262 



282 



283 



286 



310 



336 



SECTION 



Pleurocystis 348 



The Species and their Distribution 390 



Diagnostic Characters of the Species 394 



P. squamosa 403 



P. squamosa var. robusta . . 408 



P. filitexta 414 



P. elegans 420 



P. exornata 426 



P. anticostensis .... 432 



P. mercerensis .... 438 



P. Rugeri 444 



P. anglica 464 



P. procera n. sp 486 



P. quadrata n. sp. ... 501 



P. gibba n. sp 520 



P. foriolus n, sp 535 



Key to Species .... 551 

 Relations of British to American 



Species 553 



C. General Conclusions — 



I. Distribution 559 



II. Anatomy 569 



III. Taxonomy 576 



IV. Morphology and Bionomics . . . 578 



D. List op Papers and Works referred to . 615 



E. Explanation of Plates I.-VI. 



F. Index. 



species found in Girvan are in italics.) 



A. INTRODUCTION. 



§ 1. The Scottish specimens described in this memoir are all the property of 

 Mrs Robert Gray, and I am exceedingly indebted to her, not only for entrusting them 

 to me for description, but for allowing them to remain in my hands for a lengthy 

 period. None of the collections of the Geological Survey, nor those of Glasgow 

 University, contain any cystids from Girvan. Besides her Cystidea, Mrs Gray has 

 submitted to me her Crinoidea and several interesting specimens of Edrioasteroidea. 

 For the present we are concerned solely with representatives of the Class Cystidea as 



TRANS. ROY. SOG. EDIK, VOL. XLIX. PART II. (NO. 6). 48 



