864 The American Naturalist. [October, 
veins is not apparent, unless they may in some way be correl- 
ated with the anomalous position of the cardiac parts. These 
vessels nearer the heart are of smaller calibre, and on account 
of their twisted condition must retard the flow of blood consid- 
erably, the enlargements, then, may function as reservoirs for 
a reserve blood supply. 
Such factors as gravity, pressure, mode and direction of 
progression would militate against the view of a post-natal 
development of this anomaly and would render more plausi- 
ble the idea that it was due to some congenital or fortuitous 
embryonic condition. 
The accompanying figure was traced from a photograph 
enlarged three diameters, the veins are shaded; the dotted 
lines indicate vessels that were too deep or insufficiently dis- 
sected to show at the time of photographing, and have been 
filled in freehand. 
Specimens of Eutænia sirtalis, Tropidonotus sipedon, Crotalus 
horridus, and Python molurus were used for controls. Among 
them some interesting facts were observed which may serve as 
a basis for a future paper. 
Reference letters. a, common aorta; av, azygus vein; ca, 
carotid artery; cva, cervical artery; l, lung; la, left auricle; 
lao, left aorta; Jj, left jugular; cw, esophagus; p, postcava; pa, 
pulmonary netery - pe, pericardium; ra, right auricle; rao, 
right aorta; tr, trachea; v, ventricle. Magnified 2 diameters. 
