INSECT ABDOMEN SNODGRASS 



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5. Second lateral tergosternal muscle. — Origin dorsally above 4 

 on lateral part of seventh terguni (fig. 43 B) ; insertion ventrally on 

 lateral margin of seventh sternum (A). In the queen there are two 

 branches to this muscle, a short outer group of fibers arising on the 

 seventh tergum belov^ the spiracles being inserted on the sternum 

 along v^ith the fiber of the inner group. 



6. Occlusor of the spiracle.- — A small muscle between ends of 

 closing valve of seventh spiracle (fig. 43 B). 



/, Dilator of the spiracle. — A long slender muscle arising on 

 margin of seventh sternum just before lateral apodeme ; inserted 

 on lower end of closing valve of seventh spiracle (fig. 43 B). 



Fig. 43. — Musculature of posterior abdominal segments of Apis mcllifica, 

 worker. 



A, muscles of fifth, sixth, and seventh sterna. 



B, muscles of right half of seventh segment and of right spiracular plate of 

 eighth segment, mesal view. 



8. Intersegmental sternotergal muscle. — Origin on anterior apo- 

 deme of seventh sternum (fig. 43 A, B) ; fibers in the worker con- 

 vergent posteriorly to insertion on a tendon attached to end of ven- 

 tral anterior point of spiracular plate of eighth tergum (B), but in 

 the queen (fig. 44 C) attached directly to anterior lobe of spiracular 

 plate. This muscle cannot be homologized with any muscles of the 

 preceding segments, since no muscle in the latter segments has cor- 

 responding connections. 



p. Median internal ventral muscle. — Present only in the queen 

 (fig. 44 B). A short, thick, conical muscle arising anteriorly on ante- 

 costa of seventh sternum {VIIS) in position of the usual median 

 ventrals (fig. 43 A, vim); fibers divergent posteriorly to insertion 

 on anterior wall of corresponding lateral pouch of genital chamber 

 (fig. 44 B, e) . Not mentioned by other writers. 



