150 Ww. A. KIDD, ESQ., M.v., B.S., M.R.C.8., F.Z.8., ON 
as the stag-bettle, or the equally tough covermg of Pulex 
irritans (or the flea), there are numerous species with 
delicate protecting hairs, or with appendages on the 
terminal portion of the abdominal segment, such as the 
pincers of an earwig, or the sting of a bee or wasp. Then 
there are protective resemblances in this order, marvellous 
cases of mimicry, warning colours, and recoguition markings— 
all eminently protective to their possessors. Further details 
of this great group cannot be considered here. Lord 
Walsingham considers that only about 10 per cent. of all 
existing species have been described, and these are calculated 
to number 250,000. We may simply enumerate the better 
known forms —ants, wasps, bees, saw-flies, flies and fleas, 
butterflies and moths, beetles, dragon-flies, may-flies, white 
ants, crickets, grasshoppers, cockroaches, earwigs. ‘The 
simple mention of the more or less familiar forms of insect 
life bring up before the mind a perfect wealth of contrivances 
for the protection of the bodies of their possessors. 
In the Arthropoda (Crustacea, spiders), so called because of 
their pointed limbs, there is, instead of the calcareous 
skeleton of sea-urchins and the like, a chitinous external 
skeleton of the organic horny chitin, secreted by the 
integument. ‘lhe immense variety of forms which this 
great family of animals exhibits will excite our admiration 
as showing the beautiful adaptation of their protecting 
structures for diverse environments—the hard carapace and 
armour of the limbs in crabs, lobsters, crayfish, to say 
nothing of acorn-shells, king crabs, hermit crabs, barnacles, 
shrimps, sandhoppers, water fleas among the smaller forms. 
The power possessed by the young among these Arthropoda 
of shedding their protective covering during growth is 
Nature’s method of dealing with these young and sting 
lower animals. The “jointed” young ones have a simple 
method of adapting their coats to their growing bodies and 
just shed their protecting “chiton” when it is too tight, 
remain quiet and in a temporarily timid state for a few days, 
no longer indulging in their favourite battles, and devote a 
little time to the secreting of a new “chiton” from their 
soft integument. They are then ready once more for the 
struggle of their life, offensive and defensive. 
The Arachnida or spider family, im which hundreds of 
British forms alone of spiders are known, includes spiders, 
scorpions, mites, “ harvestmen ” and certain parasites. 
In many the integument is not hardened for protection, 
