PROBOSCIS OF THE GNAT. 601 



either four or five joints. The second is the Erachocera, or 

 Short-horned Diptera, in which the antennae have not more 

 than three distinct joints, and the palpi not more than two 

 joints, and often only one. 



The first Division embraces tlfose insects which are popularly 

 known as Gnats and Daddy-long-legs, and scientifically as 

 CulicidiE and Tipulidoe. We will begin with the former, and 

 take as an example the Common GtNat {Culex pipiens), the 

 male of which is represented on Woodcut LXIX. Fig. 3. 



In this family, the parts of the mouth are developed into a 

 long beak, rather thickened at the end, and being generally 

 about half as long as the head and body of its owner. The 

 beak is better studied from a female than a male specimen, as 

 only in the former is the complicated structure fully developed. 

 The beak consists altogether of seven pieces, some being used 

 as lancets, which the insect can drive into the substances on 

 which it feeds, and the others act as sheaths or strengthening 

 pieces. Owing to the very small size of the Gnat the dissection 

 of the beak is a very difficult process. Mr. Westwood, how- 

 ever, has succeeded in accomplishing it, and his account is 

 briefly as follows. ' All the parts of the mouth of a mandibu- 

 lated insect are here observable. There is a broad and hollow 

 lancet-like piece, representing the upper lip (which is the 

 most robust part of the mouth, except the labium) ; a pair of 

 slender, needie-like pieces, as the mandibles, which are serrated 

 on the outside at the tip ; a second pair of similar, but much 

 more slender organs, dilated at the base, representing the 

 maxilla, to the bases of which the palpi are attached ; a very 

 slender, needle-like instrument, representing the tongue, and 

 the outer tubular canal, in which the others lodge when at rest, 

 representing the lower lip.' 



I have slightly abridged the above description, and inserted 

 the italics, in order to point out more strongly the analysis of 

 the parts, so that the reader may see that the beak of the Gnat, 

 with its apparatus of lancets and suction-tube, is formed of ex- 

 actly the same elements as the mouth of the Stag-Beetle which 

 is represented on page 9. 



I strongly recommend any reader who has access to a micro- 

 scope to examine carefully the head and thorax of the Gnat, 

 both male and female. The Gnat is a singularly unpleasant 



