342 ZOOLOGY. 
Order 5.  Arthrogastra.—In ths group belong scor- 
pions (Fig. 313), false scorpions (Fig. 314), the whip scor- 
pions, and the harvest-man (Phalangiuwm). In all these 
forms the abdomen is plainly segmented, the segments not 
being visible in the mites or spiders. Usually the maxillary 
palpi are much enlarged, and end in claws. The scorpion 
is viviparous, the young being brought forth alive. The 
young scorpions cling to the back of the mother. The sting 
of the scorpion is lodged in the tail, which is perforated, 
and contains in the bulbous enlargement an active poison. 
Though producing sickness, pain, and swelling in the arm, 
the sting of the scorpion is seldom fatal. 
The little false-scorpions (Chelifer, Fig. 314) often occur in 
books, under the bark of treds, and under stones. The whip- 
scorpion is confined to warm countries. Thelyphonus gigan- 
teus Lucas occurs in New Mexico and Mexico. Its abdomen 
ends in a long lash-like appendage. Its bite is poisonous. 
The harvest-men, or daddy-long-legs, are common in dark 
places about houses. They feed on plant-lice. Our common 
species is Phalangium dorsatum Say. 
Order 6. Araneina.—The spiders are always recogniza- 
ble by their spherical abdomen, attached by a slender pedicel 
to the head-thorax. They breathe, like the scorpions, both 
by lungs as well as by trachex, and the young resemble the 
parent in having four pairs of feet. 
The development of the spider has some peculiarities not 
found in the higher insects. The egg undergoes total seg- 
mentation. The germ is somewhat worm-like, as in Fig. 
315, then, as in C, the primitive band forms, with head and 
tail end much alike. Afterward (Fig. 316) the head ac- 
celerates in development, and the appendages begin to bud 
out, six pairs of abdominal limbs appearing and then totally 
disappearing, except the three pairs of spinnerets, as if the 
spiders were descended originally from some Myriopod-like 
form. The mandibles are vertical, and end in hollow points, 
through which the poison exudes, the two poison-glands 
being situated in the head. The male spider is usually 
much smaller than the female; the latter lay their eggs in 
silken cocoons. The tarantula (ZLycosa) usually lives in 
