286 



AMERICAN TESTUDINATA. 



Part II. 



second, or first of the second contraction, systole of the auricles, etc. The whole 

 rhythm was remarkably regular, except some variation in the measure of the last 

 four seconds, which, as stated above, were generally thus divided into two pairs; 

 but sometimes this division was not distinctly marked, the filling of the auricles 

 beginning already in the fourth or even in the third second. As we have not 

 found any important structural differences in the hearts of the most different 

 fiimilies of Turtles, we are induced to believe that the rhythm observed in Emys 

 rubriventris is probably the general rule for the contractions of the heart in all 

 Turtles. This rhythm exhibits great uniformity, not only in the duration of the 

 contractions as a whole, but also in the measure of its successive steps. 



Three large vessels, intimately connected at their basis, which is sometimes 

 supported by a cartilaginous frame, arise from the ventricle. Two of them, car- 

 rying I'ed blood, soon form one common trunk, the aorta ; but before this takes 

 jjlace, each of them sends off" many vessels, namely, to the right the arteria 

 anonyma, from which soon start the arterite carotides and subclavise, and to the 

 left the arteries of the stomach and mesenterium. 



The venous system of Turtles agrees with that of other Reptiles. Two venae 

 anonymse from before, and two from behind, the umbilical veins of Bojanus, open 

 into the sinus venosus, which pumps the blood into the right am'icle. It is char- 

 acteristic of the Turtles, that the venae vertebrales — vena azygos of Bojanus, of 

 which there are two, as in Saurians, while in Ophidians there is only one — run 

 above the ribs in Turtles, while in all other Reptiles they run below the ribs. 

 We find such veins in Turtles above the transverse processes of the vertebrae 

 all along the dorsal column, and also in the neck and tail. There are more- 

 over some veins, peculiar to Turtles, running from the liver directly to the heart, 

 while in other Reptiles the vena cava receives all the veins of the liver. The 

 blood of Turtles does not show different features from that of other Reptiles.^ 



^ Its constituents, and its changes by starvation, 

 thirst, etc., have been recently illustrated by Joseph 

 Jones, q. a., p. 279. When taken from fresh speci- 

 mens, the specific gravity of the blood of different 

 Turtles varies from 1025 (Chelydra serpentina) to 

 1034 (Emys reticulata.) The amount of solid constit- 

 uents in 1000 parts varies from 105 (Chel. serpen- 

 tina) to 156 (Emys serrata.) The water in 1000 

 parts of blood varies from 895 (Chel. serpentina) to 

 843 (Testudo polypliemus) ; the dried organic con- 

 stituents (blood globules) vary from 56 in Chel. ser- 

 pentina to 87 in Testudo polypliemus. Thus, as was 

 to be expected, the blood of water Turtles is more 



watery than that of land Turtles. Jones (p» 23) no- 

 tices another diiference in the color of the serum, 

 namely, that, while in some Turtles (Testudo poly- 

 pliemus) this color is light yellow, as in most Mamma- 

 lia, Birds, Reptiles, Batrachians, and Fishes, it is 

 golden in some Emydoidas, (Emys serrata, reticulata, 

 concentrica,) as it also is in the black Turkey Buzzard 

 (Cathartes atratus.) With reference to the influence 

 of hunger on the blood, we find the following experi- 

 ment related in the same paper. Emys concentrica, 

 recently captured, had on the 16th of June a weight 

 of 14,285 grains. Kept without food and drink for 

 forty days, weighed, July 23d, 11,400 grains. Loss, 



