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PATTEN AND REDENBAUGH. 



[Vol. XVI. 



supply the appendages, and the haemal nerves {h.n) supply 

 the body portion of the metamere. 



Close to the ganglion each haemal nerve gives off two small 

 nerves; one of these joins a plexus supplying the longitudinal 

 abdominal muscles, the other divides into two portions, the first 

 going to a haemo-neural muscle, and the second to the intestine. 



s.cn 



men. 



Kn. 



-nn 



Fig. 8. — Diagram of typical abdominal neuromere. 



a.g., abdominal ganglion; ^.(5.«., external branchial nerve ; .f.«., gill nerve ; /z.w., haemal 

 nerve; i.b.n., internal branchial nerve; i.71., intestinal nerve; in.n., integumentary nerve; 

 l.s.n., lateral sympathetic nerve; tn.c.n., median cardiac nerve; «.«., neural nerve; /.«., 

 pericardial nerve; s.cn., segmental cardiac nerve; h.n.m., nerve to haemo-neural muscle; 

 int., nerve to intestine; l.a.m., nerve to longitudinal abdominal muscles; //., nerve to plexus 

 in tissues surrounding the intestine. 



The intestinal portion generally communicates, outside of the 

 intestine, with a plexus which unites the corresponding nerves 

 of successive neuromeres. 



At some distance from the ganglion the haemal nerve sends 

 haemally a cardiac nerve {s.cn.). This communicates by a 

 recurrent branch with the lateral sympathetic {l.s.n.) which 

 supplies the branchio-thoracic muscles. Another recurrent 

 branch of the cardiac nerve joins the pericardial nerve {p.n), 



