Fig. 123. — Median longitudinal section through the European crayfish show- 

 ing parts of body appendages and internal organs, aa, artery to antenna ; 

 ab, abdomen ; an, anus ; hd, bile duct ; 6/4, great claw ; bm, ventral nerve ; 

 cs, stomach ; cth, cephalothorax ; em, muscles of back ; fm, muscles of ven- 

 tral side ; g, brain ; h, heart ; hd, large intestine ; Ir, liver ; md, small intes- 

 tine ; 0, opening in heart ; oa, artery to eye ; oaa, dorsal artery to abdomen ; 

 oe, gullet ; pi, 1-5, swimmerets ; pl^, tail ; jys, hinder part of stomach ; sa, 

 arterj^ along sternum ; t, testis (also tail) ; uaa, artery to abdomen ; vd, duct 

 from testis ; vdo, outer opening of duct. 



121 



