HOW ANIMALS EAT. 
53 
The Arthropoda exhibit a great variety of means for 
procuring nourishment, in addition to the suctorial com 
trivances already mentioned, the innumerable modifica¬ 
tions of the mouth corresponding to the diversity of food. 
Millepedes, Caterpillars, and Grubs have a pair of horny 
jaws moving horizontally. The Centipede has a second 
pair of jaws, which are really modified feet, terminated 
by curved fangs containing a poison-duct. The Horse¬ 
shoe Crab uses its feet for prehension, and the thighs, or 
basal joints, of its legs to masticate the food and force it 
into the stomach. The first six pair of legs in the Lob¬ 
ster and Crab are likewise appropriated to conveying food 
into the mouth, the sixth being enormously developed, 
and furnished with powerful 
pincers. Scorpions have a 
similar pair of claws for pre¬ 
hension, and also a pair of 
small forceps for holding 
the food in contact with the 
mouth. In their relatives, Fig. IS.—One of the Fangs, or Perforated 
the Spiders, the claws are Mandibles, of the s P ide, 
wanting, and the forceps end in a fang, or hook, which is 
perforated to convey venom. 20 
The biting Insects, as Beetles and Locusts, have two 
pairs of horny jaws, which open sidewise, one above and 
the other below the oral orifice. The upper pair are called 
mandibles; the lower, maxillae. The former are armed 
with sharp teeth, or with cutting edges, and sometimes 
are fitted, like the molars of quadrupeds, to grind the 
food. The maxillae are usually composed of several parts, 
some of which serve to hold the food, or to help in divid¬ 
ing it, while others (palpi) are sensory. There is generally 
present a third pair of jaws —the labium — which are 
united in the middle line, and serve as a lower lip. They 
also bear palpi. The Mantis seizes its prey with its long 
