3366. In other respects the foramen ovale is not a true opening, but a bifurcation of the vena cava, one branch of which passes into the right, the other into the left ventricle, as I have demonstrated in the 'Beyträgen zur Anatomie' (Frankfurt bei Wesche), in treating of the calf's heart.
3367. There are generally no foramina in the body, but only fissures without orifices.
Abdomen.
3368. The digestive organs are pretty similar to those in Fishes, as is exemplified by the intestine, liver, and spleen; the digestive process is, however, more energetic, and frequently aided by venom or poison.
3369. The sexual parts are perfect. The first true testes and ovaria have originated. The tegumental formation has consequently passed over at the extremities into a glandular, because the vascular system preponderates. Even in the highest Fishes, such as the Rays and Sharks, the testes and ovaria are still not developed to the extent which they are in Reptiles.
3370. In the female the oviducts pass together as complete cornua into an uterus. In the male the seminal ducts are still indeed separate, yet the two bodies or crura of the penis are frequently developed, and continue separate in the Serpents and Lizards, but are connate in the Tortoises.
3371. The kidneys are distinct and symmetrical; their ureters usually unite into a large urinary cyst. Thus, the sexual lung is also significantly developed.
3372. Many of these urinary cysts split, as in the Tortoises, into two cornua. This is the form under which the bladder again occurs in Birds, where its two cornua have been incorrectly termed cœca, but the urinary bladder rectum, because the intestine opens into it.
3373. In Reptiles also there is a cloaca or sexual orifice, into which all the sexual apertures meet together.
The ova of Reptiles possess a vitellus and albumen, and are surrounded by a membranous or sometimes by a calcareous shell.