176 



EVENINGS AT THE MICROSCOPE 



sents the lower lip (labium)] it slightly swells toward the 

 tip, where it forms a round, nut-like knob, covered with 

 exceedingly minute papillae, and no doubt constituting g, 

 highly sensitive organ of touch. For the greater part of 

 its length it is covered with lined scales, and with short 

 arched hairs, like the antennae, while 

 each side of its base is guarded by 

 a labial palp of three joints. 



On applying a graduated pressure, 

 slowly increased to actual contact of 

 the plates (or as near an approxima- 

 tion to it as we can effect), we see 

 first that the nut- like tip of the 

 labium expands into two concave 

 leaves, like the bracts of a bud, and 

 displays two pairs of more delicate 

 leaves within them. Then, from a 

 groove along the upper side of the 

 labium, spring out several filaments 

 of great elasticity and of the most 

 delicate tenuity. One pair of these 

 represent the mandibles; they con- 

 sist each of a very narrow blade 

 with a stronger back like that of a 

 scythe. Their tip is brought to a 

 most acute point, and the edge in immediate proximity to 

 this is cut into about nine teeth pointing backward: the 

 rest of the edge is smooth, but the whole blade is crossed 

 by a multitude of oblique lines of great delicacy, which 

 may be intended to keep the edge constantly keen. 



Next come the maxillae, or lower jaws, horny filaments 

 as long as the former, but still more delicate, constituting 



LANCETS OF FEMALE GNAT. 



a, labium: 6, 6, mandibles; 

 c, c, maxillae; d, tongue; e, 

 labrum. 



