FIG. 3. Didelphis virginiana (Didelphidae, Didelphimorphia), representation of adult cephalic venous tree in ventral aspect, based on corrosion cast illustrations and descriptions by Dom et al. (1970: figs. 4, 5). Original authors' verified identifications (altered as necessary to conform to our terminology) are in regular type; italicized type and bold numbers represent additional identifications made for this paper (see key; color scheme as in fig. 1). Dorsal petrosal sinus, said to be present in this species (but see Shindo, 1915), is omitted. Craniopharyngeal canal, whatever its function, not depicted (foramen is present in Didelphis AMNH M-217731, fig. 2C). Right/left differences in vessel calibers probably represent natural variation or possibly distortions caused by latex injection. Dom et al. (1970: 494) state that "Plexus vertebralis internus ventralis appears to be the major pathway for drainage of the dural venous sinuses," but in our terminology this description should apply to vertebral vein per se, draining to craniospinal venous system. Internal plexus may instead be represented by relatively small vessels beneath brain stem. Key: con, confluence of transverse canal veins (rostral branches) (dark blue); cs, cavernous sinus (light gray); ejv, external jugular vein (dark gray); evps, extracranial continuation of ventral petrosal sinus (orange), here inferred to directly anastomose with vertebral vein; fv, facial vein (dark grey); icv + bvp, internal carotid vein and basicranial venous plexus (purple); ijv, internal jugular vein (light blue); mxv, maxillary vein (dark gray); ovp, ophthalmic venous plexus, including ophthalmic vein (dark gray); pglv, postglenoid (emissary) vein (dark grey); pvp, pterygoid venous plexus (aquamarine); tbs/le, rostral portion of transverse basicranial sinus and lateral extension (mottled green); tcv (rbv),