Lancelet Small 320×60 Medium 640×121 Large 1024×193 Download Tiff Original 2400×453 | (199.4 KB) Description "Lateral view of Amphioxus. The notochord runs from tip to tip. t., Tentacular cirri; G., reproductive organs; a.p., atriopore; a., position of anus; 40 and 62, indicate number of myotomes." -Thomson, 1916 Keywords amphioxus, atriopore, cephalochordata, cirri, label lancelet parts, myotomes, Notochord, primitive chordate Galleries Microorganisms Source: J. Arthur Thomson, M.A., LL.D. Outlines of Zoology (New York, NY: D. Appleton & Company, 1916)