Fig. 4: Interpretative drawings of Youti yuanshi.

a, Organ system disposition in sagittal view. Dotted lines denote location of sections shown in e,f. b, Organ system disposition in transverse view. c,d, Head, from lateral perspective (c) and as medial transverse section (d). e,f, Transverse sections through trunk at location of digestive glands (e) and transverse membranes (f). g–j, Coronal sections through head, from ventral (g) to dorsal (j) planes. Colour scheme as in Fig. 1.