THE MICROSCOPE IN ZOOLOGY, 73 



menoptera as the bees, wasps, &c. there often exists 

 a beautiful apparatus for connecting together the two 

 wings on either side, so that they may present one 

 large flat surface wherewith to strike the air and not 

 overlap one another ; along the front edge of the hind 

 wing there is a row of curved hooks ; the front wing 

 near its base is doubled over so as to form a groove 

 or slit into which the hooks fasten. You will see this 

 structure readily enough in the wings of the wasp. 

 In some insects the wings are strengthened by a thick 

 layer of horny substance intervening between the two 

 membranes, as in the Coleoptera, or beetle tribe, where 

 the front wings are no longer instruments of flight, 

 but coverings for the hind wings. In the Orthoptera 

 (grasshoppers, crickets, &c.) the front wings contain 

 much horny matter, but they are not consolidated to 

 the same extent as in the beetle tribe. If you will 

 examine a fly or other two-winged insect, you will 

 notice at the base of each of the front wings two 

 small projecting organs (halteres), the rudimentary 

 representatives, it is believed, of the posterior wings. 

 What is the function of the halleres ? Dr. Braxton 

 Hicks considers they minister to the sense of smell. 

 Mr. Lowne, in his recent excellent monograph on the 

 anatomy of the blow-fly, thinks they are organs of 

 hearing. Each haltere is a little fleshy cylinder ter- 

 minating in a small knob, having a thickened base 

 clothed with fine hairs. The globular extremity is 

 hollow, according to Mr. Lownes, and contains 

 numerous round spots, which he regards as otoconia. 

 The wing of the house-cricket contains the apparatus 

 by means of which its well-known characteristic 

 sounds are produced. I have a specimen before me 

 as I write. On each of the upper wings there is a 

 large clear space of a sub-triangular form, bounded 

 on one side by a thick dark-coloured nervure with 



