MANUAL OF NATURAL HISTORY. 273 



sects ; the Water-Mites (Hydrachnidee), live in the 

 water; while others again are found crawling slowly 

 about the leaves of various shrubs* One species, 

 called the Red-Spider (Gamasus telarius), is a great 

 pest to nurserymen and gardeners, producing much 

 injury to plants in hot-houses ; another well-known 

 member of this tribe is the little Harvest-Bug (Lep- 

 tus autumnalis), the bite of which occasions a pain- 

 ful irritation in those employed in the fields. 



The Sea-Spiders form the connecting link be- 

 tween the Crustaceans and the Arachnidans ; the 

 Pycnagonidce are parasitic upon Whales ; the Nym- 

 phonidce, harmless, inert, and slow-moving crea- 

 tures, take up their abode among madrepores and 

 branching corals. 



III. CLASS.— ARACHNIDANS (Arachnida). 



Head and thorax united, forming a cephalothorax ;. 

 eyes simple ; antenna none ; feet eight, formed for 

 walking ; no regular metamorphosis. 



I. S UB-CLASS. — Pulmonary- Arachnidans 



(Pulmonaria). 



Respiration by means of pulmonary sacs ; eyes 

 6—12. 



I. ORDER. — Spiders (Araneidae). 



Palpi simple, pediform ; mandibles armed with a 

 moveable, perforated claw emitting a poisonous 

 liquid ; abdomen not jointed, terminating in spin- 

 nerets, n 5 



