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of the Galapagos Tortoise', 



459 



work. The cavity of the ventricle is single, measuring 

 two and three fourths inches from side to side and suffi- 

 ciently large midway to allow the passage of the index 

 finger ; very much more free on right side than on left. 

 The auriculo-ventricular valves are thin and membra- 

 nous and stand out on each side from tlie septum over 

 the cavity of the ventricle. That on the right side is 

 much the largest; measuring an inch and a half along its 

 free edge, and two thirds of an inch from the base to the 

 free edge at its broadest part ; superiorly, it turns back- 

 wards and terminates bluntly on the inner surface of the 

 ventricle ; inferiorly, it inclines to the itght, becomes quite 

 pointed and is inserted into the upper part of a large 

 fleshy column, which by its action would tend to shut 

 the valve; this column makes part of the inferior parietes 

 of the right side of the cavity of the ventricle, running 

 its whole length from behind forwards, inclined to the 

 right, forming a kind of septum and probably having for 

 its especial object to direct the blood into the great ves- 

 sels. The free edge of the valve on the left side is 

 eleven lines, and its broadest part five and a half; the 

 two extremities turn down equally and are attached, the 

 inferior to the inner surface of the ventricle, the superior 

 to several fine, muscular bands which pass off towards 

 the left side and direct the blood into the spongy wall of 

 the ventricle. Just at the opening of the right auricle 

 into the ventricle there is an accessory valve, an inch and 

 a fourth long, and about a line in width, of a semi-lunar 

 ' form, with a sharp edge, and commencing just where the 



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large yalve terminates on the fleshy column ; nothing of 

 the kind was found on the left side ; in the Testudo 

 Indica Dr. Grant found it at both the auriculo-ventricular 

 openings. The three great vessels arise from the supe- 



