BLOOD VESSELS 



207 



the ventral nerve cord and ventral thoracic artery. From this a 

 series of afferent branchial sinuses carries the blood to the gills, 

 where it is oxygenated. From the gills it passes by efferent 

 branchial sinuses to the pericardial sinus. Part of the blood from 



Fig. 139. — A male crayfish dissected from the dorsal side, after injection of 



the arteries. 



a.c, ala cordis ; a.g.m., anterior gastric muscle ; ant.a., antennary artery ; c.p.m., cardiopyloric muscle; 

 car., cardiac ossicle ; d.ab.a., dorsal abdominal artery ; f.c, part of filter chamber, blue coloured in 

 fresh specimens ; fl.m., flexor muscles of abdomen ; g.a., gastric artery ; h.g., hind-gut ; ht., heart ; 

 Ir., liver; md.tn., muscle of mandible; op.a., ophthalmic artery; 05., ostium; p.g.m., posterioi 

 gastric muscle; prv., proven triculus ('cardiac' division) ; py., pyloric ossicle; ts., anterior lobf 

 of testis ; ts', posterior lobe of the same : v.d., vas deferens. 



