Peo Ps ey el Olas. OPO Hon DTA N 
MUSEUM. 
II].—ANNULELLA GEMMATA, A NEw AND REMARKABLE 
BRACKISH-WATER HLYDROID. 
By James Rircuie, M.A., D.Sc., The Royal Scottish Museum, 
Edinburgh. 
(Plates XXX, XXXa.) 
CONTENTS. 
Page 
Introductory ae oe th peak 1540 
Provenance and Habitat ae ae bee 542 
Description of the Hydroid 
Habit ae ie be. jac 42 
Structure of the Hydranth 
Form and Dimensions Ai ae ae 543 
Tentacles os sa no ee SA: 
Cnidoblasts zd, LBs os hat sel, 
Hydranth Body _... Be im io SAG 
Methods of Reproduction 
Sexual oe ee be =. ee S50) 
Asexual 
Lateral Budding _... sie 308 ws 552 
Longitudinal Fission ie vi: ne 552 
The Basal, Bulb 
Position and Appearance _... a Hee 
Detailed Structure ets Best TsBESRS 
Origin and Development _... 4 vis 555 
Significance ee te 550 
The Relationships of Annulella gemmata 
Unattached Hydroids Sas ae eet SO 
Tentacles and Cnidoblasts aes tn sere 557 
Budding... a aa ee, Bev S5C 
Analogues of the Basal Bulb ta ee N eis ty OZ 
Basal Transverse Fission ace a ree S04: 
Systematic Position of Annulella gemmata  ... fe SOS 
Generic and Specific Diagnoses of Annulella gemmata, 
nov. gen. et sp. mt ats a on sy/ 
List of Works referred toin Text ... nd. 37, 
The hydroid described in the following pages stands in several 
respects by itself. It combines in its structure and life-history 
peculiar features which are either new or have hitherto been 
found isolated in different species. Among these peculiarities are 
to be reckoned the occurrence in the vegetative hydroid phase of 
an alternation of free and fixed stages, the adoption of such singular 
methods of multiplication as the setting free of planula-like buds 
