CHAPTER XX. 



INVERTEBBATES. 



A Pool and its wonders — The "Water Spidek — Its sub-aquatic nest — Conveyance 

 of air to the nest — ^The diving-bell anticipated— Character of the air in the 

 nest — Mr. Bell's experiments upon the Spider — Life of the Water Spider — The 

 Htdkachna — The Caddis Flies and their characteristics— Sub-aquatic homes 

 of the Larva— Singular varieties of form and material — Life of a Caddis — De- 

 scription of nests in my own collection — Fixed cases, and modification of Larva 

 — Singular materials for nest-building — Corals and their general history — ^The 

 Coral of commerce — Development and extension of the Coral — How fresh 

 colonies are founded — Various Corals and their growth — Submarine tube- 

 makers — The Serpuls and their general habits — The Operculum of the 

 Serpula — The Terebellb and their submarine houses — The Caddis Shrimp — 

 Kemarlcable analogy. 



When I was a very little boy, I was accustomed to spend much 

 time on the banks of the Cherwell, and used to amuse myself 

 by watching the various inhabitants of the water. Animal life 

 is very abundant in that pleasant little river, and there was one 

 favourite nook where a branch of a weeping-willow projected 

 horizontally, and aiforded a seat over the dark deep pool, one 

 side of which was abrupt and the other sloping. 



Here the merry gyrini ran their ceaseless rounds, and the water- 

 boatmen rowed themselves in fitful jerks, or lay resting in a 

 contemplative manner on their oars. Now and then an unlucky 

 insect would fall from the tree into the water, and then uprose 

 from the dark depth a pair of dull eyes and a gaping mouth, 

 and then, with a glitter as of polished silver, the dace would 

 disappear with its prey. In the shelving part of the pool the 

 caddis-worms moved slowly along, while the great dyticus beetle 

 would rise at intervals to the surface, jerk the end of his tail 

 into the air, and then dive below to the muddy bottom. This 

 spot was much favoured by the nursemaid, for she had no trouble 

 in wat<;hin<: me, as long as I could sit on the branch and look into 



