862 The American Naturalist. [October, 
“the Thebesian valve covers the opening of the coronary vein,” 
whereas that valve over the orifice of the coronary vein is known 
as Vieussens valve, in honor of its discoverer. According to 
Heath, “ the coronary valve guards the opening of the coronary 
sinus.” But Thebesius was the first to make known the form and 
position ofthe valve over the termination of the sinus, and in his 
honor it is called the Thebesian valve. 
According to Marshall, “the Thebesian valve is present in 
every instance in which the coronary sinus receives blood from 
the heart alone, as in man, monkey, dog, and cat, but absent in 
those animals that have a left azygos or left precava.” Since the 
Thebesian valve was found only in man, monkey, and rabbit, and 
not in the cat, panther, and dog, where Marshall says it ought to 
exist, and one is present in the rabbit, where he says it ought not 
to be, this generalization will not hold good. A valve existed 
over the orifice of the middle cardiac vein in every heart 
examined, and as it is not named in any work as far as I know, I 
would suggest that it be called coronary valve. 
The Coronary Sinus——Morrell says “the coronary sinus of 
the sheep is the lower dilated part of the left azygos.” Marshall 
holds that in those animals in which a left azygos or left precava 
exists it empties directly into the right auricle, and the coronary 
vein opens into it. 
Bourgery, Owen, Gegenbaur, and Howell think the coronary 
sinus is but the dilated part of the coronary vein. 
Personal observation causes me to differ from the above-named 
authors as to the homologue of the sinus. It is my opinion 
that the coronary sinus is the persistent primitive left Ductus 
Cuvieri, and that the left precava or left azygos, when they exist as 
as well as the great coronary vein empty into it; thus sending 
their blood through it to the heart. The great coronary vein 
empties into the sinus, and not in one case into an azygos, in another 
into a cava, again directly in the auricle. In support of this, Bar- 
deleben says “the left azygos as well as the left precava, when pre- 
sent, empty into the sinus. That piece of vein under discussion is 
the left Ductus Cuvieri, which does not disappear in any mamaml.” 
The Oblique Vein of Marshall—It was surprising to‘find that 

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