. Outlines of zoology. lastron; XIPHL^ xiphiplastron. The heart is three-chambered, but an incomplete septum divides theventricle into a right portion, from which the pulmonary arteries andthe left aortic arch arise, and a left portion, from which the right aorticarch issues. From the right aortic arch, which contains more pureblood than the left, the carotid and subclavian arteries are given off.The left aortic arch gites off the cceliac artery before it unites with theright. The lungs are attached to the, dorsal wall of the thorax, and haveonly a ventral investment of peritoneum; each is div

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. Outlines of zoology. lastron; XIPHL^ xiphiplastron. The heart is three-chambered, but an incomplete septum divides theventricle into a right portion, from which the pulmonary arteries andthe left aortic arch arise, and a left portion, from which the right aorticarch issues. From the right aortic arch, which contains more pureblood than the left, the carotid and subclavian arteries are given off.The left aortic arch gites off the cceliac artery before it unites with theright. The lungs are attached to the, dorsal wall of the thorax, and haveonly a ventral investment of peritoneum; each is div
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Image ID: 2AGC7RK
. Outlines of zoology. lastron; XIPHL^ xiphiplastron. The heart is three-chambered, but an incomplete septum divides theventricle into a right portion, from which the pulmonary arteries andthe left aortic arch arise, and a left portion, from which the right aorticarch issues. From the right aortic arch, which contains more pureblood than the left, the carotid and subclavian arteries are given off.The left aortic arch gites off the cceliac artery before it unites with theright. The lungs are attached to the, dorsal wall of the thorax, and haveonly a ventral investment of peritoneum; each is divided into a series CLASSIFICATION OF CHELONIA. 617 of compartments into which branches of the bronchus open. There isa slight muscular diaphragm. The filling and emptying of the lungsis helped by the protrusion and retraction of the head and legs, butthere are also swallowing movements. There are ifo vocal chords,hut there is sometimes a feeble voice.In the males, the kidney, the epididymis, and the testes lie adjacent. Fig. 334.—Scales on ventral surface of plastron ofGreek tortoise. C, Gular; H., humeral; P.^ pectoral; Ab.y abdominal;F.i femoral; A.^ anal; M.^ marginal. to one another on each side. The males have a grooved penis attachedto the anterior wall of the cloaca. There is a urinary bladder. Classification of Chelonia I. AtheC/E. Vertebrse and ribs free from carapace. Skullwithout descending processes from parietals. Sphargidse, leathery-skinned turtles, with flexible carapace. Sphargis(Dermatochelys) coriacea, the only living species, the largest modern 618 REPTILIA. Chelonian, sometimes measuring 6 ft. in length. It is widely, butnow sparsely, distributed in intertropical seas, and is said to be herbi- II. Thecophora.Dorsal vertebrae andribs fused in thecarapace. Parietalsprolonged down-wards. Includingthe following andother families:— Chelonidse, marineturtles, with fin-like feet,and partially ossifiedcarapace. They occur inintertropical seas, andbury their sof