CONTENTS. 



PAGE 



PREFACE ......•• V 



GLOSSOLOGY . . . . • • xi 



Terms applicable to tlie Hydroid Colony in general . . . xii 



Terms applicable to the Tropliosome . . • • . xi 



Terms applicable to the Gonosome . . ■ • • xm 

 Terms applicable to certain Conditions of the Hydrosome. — Names of Leading 



Systematic Groups ....•• xvii 



PART I. 



THE HYDROIDA IN GENERAL. 



PHYSIOGNOMY OP THE HYDROIDA.— DESIGN OF THE MONOGRAPH . 1 

 SYSTEMATIC POSITION OF THE HYDROIDA . • -2 



HISTORY OF THE PROGRESS OF OUR KNOWLEDGE OF THE HYDROIDA 3 

 MORPHOLOGY OF THE HYDROIDA.— TERMINOLOGY . 



I. The Hydrosoma in General 



1 . Generalised Conception of a Hydroid . 



2. General Structure.— Ectoderm and Endoderm 



3. Composite Character of the Hydroida. — Trophosome and Gonosome 



4. Orientation . . . • • 



II. Morphology of the Trophosome 



1. Hydranths . . . . • 



2. Hydrophyton . . . ■ • 



Cffinosarc and Perisarc . . . • 



Hydrorhiza and Hydrocaulus 



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