ZOOLOGY. 33 



Class ARACHNIDA. 



Head united with the tliorax {Cephalothorax). Abdomen not sepTnontod in the 

 typical forms, and never provided with limbs. Logs never more than four pairs. 

 No antennre. Eyes simple, generally more than two, and often of unequal size. 

 Like Crustacea the Arachnida moult and possess the power of reproducing lost limbs. 

 Sexes distinct. 



Order SCOllPIOIDEA. 



Abdomen indistinctly separated from the cephalothorax, and having a ' post 

 abdomen ' or tail of six joints, the terminal one of which bears a pcrf(jnited claw 

 comiimnicating with a poison gland. The maxillary palpi longer than the feet and 

 terminating in a didactyle claw or ' pincers,' with which animals are held whilst being 

 pierced and killed by the caudal sting. The scorpions are viviparous, tlio very youug 

 being carried about on the motlier's body. 



Order CHELIFERIDEA. 

 These Arachnoids, or False Scorpions as they are called, are minute and harmless 

 creatures, armed with pincers like the scorpions, but devoid of jointed tail and stiug. 



Order ACAEIDEA. 



Head, thorax, and abdomen united. JFouth either masticatory or suctorial. 



This order embraces the Mites, both Slarine, Freshwater, and Terrestrial, and 

 their variety is astonisliing. Acariis doniesticiis is the cheese mite. Leptus autumnaUs 

 the harvest-bug, which fixing on the skin, gives rise to intolerable itching. Gamams 

 coleopfironim is the mite, seen clustering round the legs of the common dung beetle, 

 from which little pest the strong beetle is helplessly unable to free himself. Atax 

 lives in the branchia; of bivalves, whilst Demodex fulliculorum lives in the sebaceous 

 follicles of man. Sareopfes scahiei burrowing beneath the skin, causes the itch in man, 

 and another mite causes the mange in dogs. The vegetable kingdom suffers too 

 from the attacks of mites no less than the animal. 



Order ARANEIDEA. 



This order embraces the spiders proper, possessing a distinctly separated abdomen, 

 eight legs, with seven joints each. Eyes simple, four to eight (two in a Cuban species). 

 A pair of poison fangs (palpi) and abdominal glands for the secretion of a glutinous 

 substance and spinning a])paratus for constructing thread for forming a snare or not. 

 There is often extreme dispai'ity in the size of males and females, the former being some- 

 times so minute as to be almost parasitic on the person of their huge spouse. Tlie eggs are 

 deposited in a silken cocoon, which in some species is carefully carried about by the 

 female beneath her abdomen, and is most carefully guarded till the young sjuders 

 emerge. The young spiders ' moult ' as they grow, liut undergo no metamorphosis. 

 A long treatise would be required to describe the various forms, liabits, modes of life, 

 dwellings, and the life history of these animals ; but so far as regards Burmese 

 species next to nothing is known. But some idea of their probable number may be 

 formed from the fact that some 500 species inhabit the British Isles, with its far 

 pooi-er insect fauna than an (.Mjual area within the tropics. Dr. Stoliczka makes the 

 following remarks on spiders : — 



" It is strange that not only dislike, but a real enmity and ill-feeling against Arach- 

 noids, seems to have taken hold of men's minds. No doubt, the few species which secrete 

 a poisonous fluid in special glands, and through its use occasionally become dangerous, 

 are the source of all this ill-feeling which has been extended to the most useful 

 animals. Harmless they certainly are on the whole, and as regards usefulness, 

 scarcely surpassed by any other class of animals. They wholly live on insects and 

 destroy a large number of those which often create great damage to either animal 

 or vegetable life. Thus they are important agents in sustaining a proper balance 

 in the economy of nature, and their usefulness actually increases, by their not being 

 dangerous in such a way, as insects often arc. 



