INSECTA. 309 



the head, the trunk, and the abdomen. On the head two compound 

 eyes are usually seen, which are very large, especially in the male ; 

 in the most, simple eyes or eyespots are also present, usually three, 

 sometimes only two in number. The antennae are placed on the 

 frons close to the eyes ; ordinarily they are, in comparison with 

 those of other orders, short. Some sub-divisions of the genus 

 Tipula L., make an exception to this, and the genera Macrocera 

 MEIG. and Megistocera WIEDEMANN are especially distinguished by 

 their long antenna?. The sucker consists of two, four, or six sharp 

 threads, which in the last case represent the upper lip (labrum), 

 the tongue (ligula), the two upper and the two under jaws. At 

 the under jaws (maxillce) or, when these are wanting, at the base 

 of the sucker, two feelers are attached, which sometimes consist of 

 five, sometimes only of two joints, or of a single joint. The under 

 lip forms an univalve sheath excavated above, in which the sharp 

 threads or stings reside by means of which these insects wound ; 

 on this part there are no feelers. The first piece of the thorax is a 

 small ring, forming a neck-ring, but the middle piece (mesothorax) 

 is large, and forms nearly the whole of the thorax. To this division 

 of the thorax the wings are attached. These are veined, usually 

 transparent as glass, and colourless, occasionally spotted ; they are 

 without that little horny point at the anterior or external margin 

 (punctum ccdlosum s. cubitale) which is seen on the anterior wings 

 of the Hymenoptera. Behind the wings there is mostly found a 

 small special appendage, a membranous scale (squama fialterum), 

 which may be regarded as a part of the wing. To the metathorax 

 the poisers (halteres] are attached, which consist of a thin pedicle 

 and a button. These halteres are also found in species that have 

 no wings. They are to be considered as rudiments of hind-wings 1 . 

 The abdomen is often united to the trunk by a small part alone of 

 the diameter of its base, and consists of from four to nine rings. 

 In the female it generally runs to a point at the posterior ex- 

 tremity ; if here fewer rings are found, it is because the last of 

 them form an ovipositor or case consisting of rings that can be 

 pushed in and out of each other, like a pocket telescope. The feet 

 are in most long and slender, and terminate always with tarsi 



1 See above, p. 252 ; comp. also WESTWOOD, Introd. to modern Classific. II. p. 500. 

 jATREiLLE regarded these parts not as rudimentary hind-wings, for he thought they 

 3re attached to the abdomen. 



