ARTICULATA. I39 



Insects which have five articulations to the tarsus are named ijenta- 

 merous. Tliose witli four are named tetramerous ^ hut as a fifth inimo\'ahle 

 and microscopic articulation has heen discovered, Burmeister names tliis 

 form crypto])entaiiierous^ and Westwood, pseudotetramerous^ a useless 

 addition of names, for, as Mulsant observes, tlie terms Tetnimera^ &c., 

 refer to the number oi free articulations. Solier goes so far as to consider 

 all the Coleoptera pentamerous ; hut even could the abortive articulations 

 he detected, the relation of the dilferent groups would not he altered,* 

 because the tarsi of the Pentaraera would still have five, and those of the 

 Tetramera four movable pieces. In the Jleteromera the four anterior tarsi 

 have fii'e^ and the posterior \ydAY four articulations. Trhnerous^ dlmerow<y 

 and monomerous tarsi are also enumerated. The anterior tarsi are some- 

 times wanting, as in Ateuchns. 



The wings, when present, are either two or four, the anterior pair being 

 aflSxed to the mesothorax, and the posterior ones to the metathorax. Some- 

 times the two pairs are equal, and when thej are of unequal size, sometimes 

 the anterior ones are the largest, as in the Hymenoptera and Lepidoptera ; 

 and sometimes tlie 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, &c.) the upper or anterior wings (named tegmina) are thicker and 

 narrower than the inferior ones, and the latter are folded like a fan. In a 

 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 ISTeuroptera have numerous reticulating nerv- 

 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 

 to a small knobbed thread {kälteres). In the Strepsiptera 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 glowworms. 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 efiected by a membrane, and in the latter case the base of 

 each segment slides within the preceding one. Tiie abdomen is more 



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