Charles F. W. McClure Sie 
-~2 
the left precaval vein opening in common with the postcava. The 
internal mammary and the subclavian veins do not present any un- 
usual characters and will not be further considered. The V. costo- 
vertebralis will be described in connection with another topic. 
.-V. 3. ment. 
V.m.e. 
V. ov. 
\.-pro (dex) 
pre(siny-7 
Fic. I]. Diagram of the veins of the head and neck of Didelphys marsupialis. 
Ventral view. 
a., small veins which collect blood from the submaxillary and sublingual glands; 
b., a vein which collects blood from the superficial muscles on the front of the neck; 
c., a vein which collects blood from the side of the larynx; cl., clavicle; do., dorsal 
portion of yenous ring; pre., precava; X., outer venous ring, formed by external jug- 
ular, axillary and cephalic veins; y., ventral portion of venous ring formed exclusive- 
ly by external jugular vein; V.a., V. azygos; V.an., V. anastomotica; V.a.p., V. 
auricularis posterior; V.ax., V. axillaris; V.cep., V. cephalica; V:c.d., V. cervicalis 
descendens; V.cy., V. costovertebralis; V.j.c.. V. jugularis communis; V.j.e., V. 
jugularis externa; V.j.i., V. jugularis interna; V.mam., V. mammariainterna; V.m.e., 
V. maxillaris externa; V.m.i., V. maxillaris interna; V.s., V. subclavia; V.s.max., 
V. submaxillaris; V.s.ment., V. submentalis; V.t.s., V. transversa scapule. 
The V. jugularis communis (V. j. c.) is a short trunk and is formed, 
on each side, through the union of the V. jugularis externa (V. j. e.) 
and the V. jugularis interna (V.j.i.). The common jugular vein re- 
ceives one tributary, the V. cervicalis descendens (V.¢c.d.), which 
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