LARVA OF LESSER HOUSE-FLY 



191 



and is continued posteriorly. These liagelliforni processes are 

 spiniferous, the spines being well developed at the bases of the 

 processes and gradually decreasing in size distally. The twelfth 

 or anal segment is provided with three pairs of these processes 

 of unequal size ; the most an- 

 terior pair is the longest on the 

 body, and the intermediate pair 

 is shorter. 



There is a series of pairs of 

 small, almost sessile branched 

 appendages (fig. 85) situated 

 near and slightly posterior to 

 the bases of the latero-dorsal 

 appendages. These were de- 

 scribed by Kieffer. Each of 

 these processes has three to 

 four branches, and they carry 

 a small nucleiform organ which 

 Chevril (1909) has also de- 

 scribed. He believes that this 

 organ is of the nature of an 

 exuvial gland and correspon- 

 dent to Verson's gland. 



On the ventral surface of 

 the body, and extending pos- 

 teriorly from segment III, there 

 is to be found a series of pairs 

 of small spiniferous papillae. 

 Between these there is on each 

 segment a transverse row of 

 four groups of spines. 



The anterior or prothoracic spiracular processes (fig. 84) have 

 usually seven finger-like lobes, though the number may vary fi-om 

 five to eight, and between the second and third lobes there appears 

 to be a small stigmatic organ. The posterior spiracular processes 

 have a trilobed appearance, but a close examination reveals their 

 four-lobed character shown in fig. 86 ; a stigmatic orifice is situated 

 at the extremity of each lobe. 



Fig. 83. Mature larva of Fannia canicu- 

 laris, L. x 17. 



a.sp. Anterior spiracular processes. 

 p.sj). Posterior spiracular processes. 



