or 
ARTICULATA. 139 
Insects which have five articulations to the tarsus are named pentu- 
merous. Those with four are named ¢etramerous ; but as a fifth immovable 
and microscopic articulation has been discovered, Burmeister names this 
form cryptopentamerous, and Westwood, pseudotetramerous, a useless 
addition of names, for, as Mulsant observes, the terms Zetramera, &c., 
refer to the number of free articulations. Solier goes so far as to consider 
all the Coleoptera pentamerous; but even could the abortive articulations 
be detected, the relation of the different groups would not be altered, 
because the tarsi of the Pentamera would still have five, and those of the 
Tetramera four movable pieces. In the /Zeteromera the tour anterior tarsi 
have jive, and the posterior pair four articulations. Zrimerous, dimerous, 
and monomerous tarsi are also enumerated. The anterior tarsi are some- 
times wanting, as in Ateuchus. 
The wings, when present, are either two or four, the anterior pair being 
affixed to the mesothorax, and the posterior ones to the metathorax. Some- 
times the two pairs are equal, and when they are of unequal size, sometimes 
the anterior ones are the largest, as in the Hymenoptera and Lepidoptera ; 
and sometimes the posterior ones, as in the Orthoptera. In the Coleoptera 
the anterior wings are converted into elytra for the protection of the true 
wings, not being used as organs of flight. The wings are composed of two 
usually transparent membranes, between which various hollow nervures are 
distributed, and filled with air from the body. In the Orthoptera (grasshop- 
pers, &e.) the upper or anterior wings (named tegmina) are thicker and 
narrower than the inferior ones, and the latter are folded likeatan. Ina 
part of the Hemiptera the base of the upper wings has a leathery texture. 
All the wings of the Hymenoptera, Lepidoptera, and Neuroptera, are of a 
uniform texture respectively. Those of the Lepidoptera are covered with 
minute scales; those of the Neuroptera have numerous reticulating nery- 
ures, and in the Hymenoptera the nervures are but few. In the Diptera, or 
flies, the anterior wings are used in flight, the posterior ones being reduced 
toa small knobbed thread (halteres). In the Strepszptera the posterior wings 
are fully developed, the anterior ones being abortive. In most of the 
orders of winged insects there are genera and species which have no 
wings; and some have wings in one sex and not in the other, as in the 
female coleoptera, known as giowworms. In one genus of Orthoptera the 
posterior wings are present, without a vestige of the anterior pair. 
Abdomen. The abdomen is attached to the metathorax, either by its 
entire breadth, or by a portion of it only. The upper surface is named the 
dorsum, and the lower one the venter. Of the nine distinct normal 
segments some are occasionally absent by a union of several into one. In 
some cases the segments of the dorsum and venter do not correspond; in 
Carabus, for example, the former has nine and the latter but five. In many 
cases the abdomen of the male has one segment more than that of the 
female, and the dorsum has generally one more than the venter. The con- 
nexion between the upper and lower parts of the same segment, and between 
the segments, is effected by a membrane, and in the latter case the base of 
each segment slides within the preceding one. The abdomen is more 
343 
