OF THE GREAT ANTERIOR VEINS. 
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lower portion into a small oblique vein and the coronary sinus (i), into whicli, at its 
junction with the oblique vein, the coronary vein (g) enters. 
Fig. 9. Outline plan carefully constructed from the heart of an embryo, measuring 
5 inches from the vertex to the coccyx. The essential stages of the metamorphosis 
of the left primitive venous trunks are so complete, that the parts now representing 
it are nearly the same as in the adult condition, viz. the trunk of the left superior in- 
tercostal vein (i), the vertical fibres beneath the left pleura (f), the vestigial fold (v), 
and the lines or streaks (/) on the left auricle. The lower persistent portion of the 
left canal of Cuvier is transformed into a short oblique vein (o) and the coronary sinus 
(.9), which are only partly seen, and which are joined by the great cardiac or coronary 
vein (g). 
Fig. 10. Heart of the same embryo. The lines or streaks (c"), the oblique vein, 
the coronary sinus (s) and the coronary vein (g) appear almost as in the adult heart. 
Fig. 11. Heart of a small foetus, still-born at the full period. The drawing is of the 
natural dimensions. The metamorphosed parts are easily recognized. The coronary 
vein (g) and sinus (s) are slit up, to show the commencing valve at their point of 
junction, and the place of opening of the oblique vein ( 0 ), which is continued up into 
the line or streak (/). 
PLATE V. 
Sketch of the under surface and left side of the heart, great blood-vessels, and root 
of the left lung, from a female aged 19 ; exhibiting the remains of the left anterior 
primitive vein, as ordinarily seen in the adult human heart. 1, 2, 3, 4, 8, 9, 10, 10, 
1 1 and e, refer to the same parts as in Plate I. fig. 1. 13. The left vagus nerve, d. Left 
innominate vein, formed by the primitive cross branch and part of left primitive 
jugular, i. Trunk of the left superior intercostal vein, formed by the part of the 
metamorphosed left jugular vein situated immediately below the cross branch in the 
neck. f. Indistinct fibrous bands, mixed with small vessels and nervous cords, shown 
after removal of the pleura, lying in the track of the previously existing vein, and 
passing down to the root of the left lung, and thence through the pericardium into 
the fold marked v. v. The vestigial fold of the pericardium, persisting after the oc- 
clusion of the corresponding part of the left canal of Cuvier. L Lines or streaks 
on the wall of the left auricle, descending from the vestigial fold to a small oblique 
vein, marked o. This oblique vein ( 0 ) enters the coronary sinus (^) close by the 
valved orifice of the coronary vein (g): together with the sinus, it forms the lower 
persistent pervious portion of the left primitive vein or canal of Cuvier. 
PLATE VI. 
Sketch of the under surface and left side of the heart and great vessels of a man, 
aged 56 years, in which there is a second superior cava on the left side, constituting 
MDCCCL. 
z 
