. Outlines of zoology. Zoology. VASCULAR SYSTEM. 573 Embedded in the mesentery below the stomach lies the rounded spleen. A whitish thyroid gland lies on the ventral surface of the trachea a short distance in front of the heart. Vascular system.—The heart is completely enveloped by the pericardium, and is three-chambered, consisting of two thin-walled auricles and a muscular ventricle. From the ventral surface of the ventricle arises the conspicuous truncus arteriosus, which is formed by the bases of the. J?,!3, Fig. 249. -Heart and associated vessels of a lizard. After Nuhn. A., Right auricle
. Outlines of zoology. Zoology. VASCULAR SYSTEM. 573 Embedded in the mesentery below the stomach lies the rounded spleen. A whitish thyroid gland lies on the ventral surface of the trachea a short distance in front of the heart. Vascular system.—The heart is completely enveloped by the pericardium, and is three-chambered, consisting of two thin-walled auricles and a muscular ventricle. From the ventral surface of the ventricle arises the conspicuous truncus arteriosus, which is formed by the bases of the. J?,!3, Fig. 249. -Heart and associated vessels of a lizard. After Nuhn. A., Right auricle; jugulars (/.), subclavians (), and inferior vena cava () enter it. V., ventricle ; tr., truncus arteri- osus ; 1, first aortic arch giving off carotids; 2, second aortic arch; , pulmonary artery; Sea., subclavian; Ao., dorsal aorta. ^4!., left auricle ; pulmonary veins (/.».) enter it. In the lizard described, the left jugular is not developed. aortic arches, and exhibits a division into two parts. From the more ventral part arises the left aortic arch, which curves round to the left side, first giving off a short connect- ing vessel (ductus Botallii) to the carotid arch. From the other division of the truncus arteriosus, a great arterial trunk arises, and this gives off the right aortic arch and the right and left carotid arches. The right aortic arch sends a ductus Botallii to the carotid arch of the right side, and then curves round the heart to join the left arch, when the two. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Thomson, J. Arthur (John Arthur), 1861-1933. Edinburgh, Glasgow and London, H. Frowde and Hodder & Stoughton
Size: 1639px × 1525px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorth, bookcentury1800, bookdecade1890, booksubjectzoology
