376 ZOOLOGY 
stand not only at the head of their own phylum, but in front 
of all other animals, man alone excepted. It is not a very 
large order, only about 25,000 species are described. All of 
these are terrestrial, and most of them inhabit the warmer and 
more temperate parts of the globe. 
The head is freely moveable, the eyes large and prominent, 
and, as is often the case in insects, they are larger in the male 
than in the female. ‘There are three ocellii The antennae 
are often crooked, and then consist of a basal joint or shaft, 
and ten to twelve shorter joints; they may be straight. 
The mouth is adapted for biting or licking; there is a 
small labrum, and the mandibles are large and stout. The 
maxillae and Jabium are elongated, palps being present in 
each case. The nectar upon which bees feed is licked up by 
the ligula, and deposited upon a sheath formed of the labial 
palps and maxillae, and in the sheath thus formed the food 
passes up to the mouth. The ligula is the front edge of the 
labium. In bees it is enormously developed, and divided 
into three lobes, the two outer of these are termed paraglossae. 
On the mesothorax are two small scales known as the 
tegulae, covering the base of the wings. 
The legs have a five-jointed tarsus, and in bees the tibia 
and tarsus, especially those of the posterior pair of legs, are 
covered with short hairs, these help to collect and convey 
home the pollen grains the bees have gathered during their 
frequent visits to flowers. 
The abdomen is as a rule pedunculated, the two anterior 
segments forming the peduncle. In the female the abdomen 
ends in an ovipositor, which in the Aculeata is modified and 
forms a sting. This complicated apparatus developes from 
six protuberances on the embryo, four on the last but one, and 
two on the last segment. These protuberances elongate and 
form a grooved process with two stylets and a pair of lateral 
sheaths, besides these there are certain supporting plates. 
The poison consists of formic acid with some fatty sub- 
stances ; it is secreted in a special gland, which communicates 
with a reservoir, this opens at the base of the grooved 
process. 
The nervous system consists of an unusually large and. 
