Transverse Thorax Small 320×196 Medium 640×393 Large 1024×628 Download TIFF Original 2400×1472 | (255.7 KB) Description Ideal section through an insect. -a, alimentary canal; h, heart; n, nerve-cord; s, stigmata; t, tracheal tubes; l, legs; w, wings. Keywords Entomology, Insect, insects, sections Galleries Insect Anatomy Source: John B. Smith Economic Entomology (Philadelphia and London: J.B. Lippincott Co, 1896)