The ventral nerve chord consists of three thoracic and eight abdominal 

 ganglia connected by commissures and with the subesophageal ganglion 

 (Figures 40, 54 — 56). The 1st abdominal ganglion is situated near the 3rd 

 thoracic ganglion in the metathorax; the 2nd abdominal ganglion is situated 

 in the first abdominal segment near its anterior margin; ganglia 3 — 6 are 

 situated in the corresponding abdominal segments or are displaced to the 

 posterior part of the preceding segment; the 7th ganglion is always situated 

 close to the 8th; both ganglia are situated in the segment immediately 

 posterior to the 6th ganglion (Figure 54) or some distance from this 

 (Figures 55 and 56); the 7th ganglion is sometimes situated near the 

 posterior margin of the 6th segment, and the 8th ganglion is situated near 

 the anterior margin of the 7th segment; both ganglia are rarely displaced 

 to the 5th segment; the 8th abdominal segment sends thick nerves to the anal 

 legs of the larva (Figure 63). 



Each of the three thoracic ganglia sends a lateral nerve to each leg; 

 the nerve has a large coxal branch before entering the leg which innervates 

 46 the dorsal part of the coxa; it then continues into the leg, branching to the 

 end of the tarsus (Figures 60—62); the pretarsus is entered by the end of 

 the tarsus (Figures 60 — 62); the pretarsus is entered by the end of the nerve 

 innervating the sensilla of the basal seta, but the sensory cell of the nerve 

 is situated in the tarsus (Figure 62) or is rarely situated in the claw 

 (Raciecka, 1949:23—52). The basal part of the claw of the anal leg is more 

 richly innervated than the distal part (Figures 63 and 64). 



(48) 



FIGURES 65—67. Maturation of sperm cells in the larva and pupa of Limnophilus 

 stigma (after Liibben): 



65 — formation of sperm tubes; 66 — transverse section through sperm tube; 67 — stages 

 of spermatogenesis: A — spermatogonium (larva); B - spermatocyte (larva); C — sperma- 

 tid (full-grown larva); D - spermatocyst (prepupa);- E — spermatozoid (mature pupa). 



43 



