"Transverse section of thorax of crayfish, diagrammatic. abm, ventral abdominal muscles; bf, leg; bm, ventral nerve-cord; d, intestine; dbm, dorsal muscles of abdomen; ep, wall of thorax; h, heart; k, gills; kd, gill-cover; l, liver; ov, ovary; pc. pericardial sinus; sa. sn, sternal artery; vs, ventral sinus. The arrow shows the direction of the blood-current." -Parker, 1900

Crayfish Thorax

"Transverse section of thorax of crayfish, diagrammatic. abm, ventral abdominal muscles; bf, leg; bm,…