CONTENTS. 



I'agc 



I. Introduction and Historical I 



II. Specimens examined 3 



III. Diagnoses of species of Ccphalodiscus 4 



IV. Coenoecium 8 



V. Exteinal characteis of the zooids 17 



\ I. Methods and General anatomy 21 



VII. Proboscis 26 



VIII. Collar (including the aims and the operculum) 30 



IX. Metasome, body or tiunk 47 



X. Stalk 50 



XI. .\limentary canal 53 



XII. Muscular system 66 



XIII. Nerveus system 71 



XIV. Vascular system 74 



X\'. Reproductive organs 81 



XVI. Budding gi 



XVII. Development 102 



XVIII. Affinities 112 



XIX. Rhahdoflcura 125 



XX. Summary of the principal results 128 



XXI. Bibliography 130 



XXII. Explanation of Plates 1— XIV 133 



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