ANALYTICAL INDEX. 349 



CHAPTER VIII. continued. 



2. TEREBELLA PECTEN, ..... PAGE 208 



Description, . . . . . . jb. 



Only one specimen occurred, . . . . . ib. 



Plate XVI. explained, ..... ib. 



3. TEREBELLA OSTRE..E, . . . . 209 



The generic name Terebella misapplied, ... ib. 



The Ostrea capable of entering a hard substance, . . ib. 



Found in the exterior of oyster shells, ... ib. 



Bears considerable analogy to the Terebella, . . . ib. 



Description, ...... ib. 



Organization modified by age, . . . . ib. 



Its habitation, a cavity adapted for its body, is lined with silk, 210 



Twelve have been found on a single shell, . . . ib. 



Plate XXVI. explained, ..... ib. 



Concluding remarks, . . . . . . ib. 



A brilliant phosphorescence belongs to some of the genus, . ib. 



Several facts merit particular investigation, . . . ib. 



The generic character, . . . . . 211 



CHAPTER IX. AMPHITRITE AND CONGENERA, . . .212 



Farther illustrations of instinct, .... ib. 



1. AMPHITRITE VENTILABRUM, The Fan Amphitrite, . . ib. 



Found fixed to a solid foundation fifty or sixty feet below the sea, ib. 



Description, '...... ib. 



Unfolds a splendid plume of many feathers, . . 213 



The animal decked with various colours, . . . 214 



Organic structure dependent on dimensions, . . 215 



Account of specimens, . . . . . ib. 



The Pennatula mirabilis, ..... ib. 



The ventilabrum still more admirable, . . . ib. 



Has the control of 50,000 living parts, . . . 216 



What the precise spirit which actuates them ? ib. 



Its architectural operations described, . . . 217 



Nothing so admirable as the operation of so many distinct organs, 218 

 Unlike the Terebella;, if once dislodged, the Amphitrite remains 



unprotected, ...... ib. 



Account of specimens, . . . . . 219 



Tube composed of earth and gluten, . . . . ib. 



Perhaps necessity urges the constant prolongation of the dwelling, 220 



