. Elementary text-book of zoology [electronic resource]. Zoology. 452 CHORD AT A. If the effect of the varying size of mammals be eUminated, a table showing degree of " cephalisation" can be formed, and this agrees generally with the recognised succession of the mammalian orders, the Metatheria, Edentata, and Efifodientia, Rodents and Insectivora taking the lowest places, followed by Ungulata, Cetacea, Carnivora, and lower monkeys, and, lastly, anthropoid apes and man. Thirdly, taking extinct mammals into account, it would appear that in mammals of similar size and bodily organisatio
. Elementary text-book of zoology [electronic resource]. Zoology. 452 CHORD AT A. If the effect of the varying size of mammals be eUminated, a table showing degree of " cephalisation" can be formed, and this agrees generally with the recognised succession of the mammalian orders, the Metatheria, Edentata, and Efifodientia, Rodents and Insectivora taking the lowest places, followed by Ungulata, Cetacea, Carnivora, and lower monkeys, and, lastly, anthropoid apes and man. Thirdly, taking extinct mammals into account, it would appear that in mammals of similar size and bodily organisation, the relative brain- weight increases with the time, as we have seen that the greatest advance from Eocene times has been cerebral. Fig. 288.—A Rete A, General appearance. B, Cross-section of the blood-vessels. C, Anastomosis of smaller and larger ve .sels. (After Ml'rie.) Blood-Vascular Sysiem.—The heart and circulatory system do not show any great adaptation throughout the class. The heart is always four chambered, and the systemic arch is only found on the left. In various regions of the body there are developed fine meshworks of blood-vessels which are termed i^etia mirabilia. These are found at the bases of the limbs in many arboreal animals which have to hang from boughs, in which case they appear to counteract the retarding effects of gravity upon the circulation, {cf. Sloth).. 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 Masterman, Arthur Thomas; Parsons, John Herbert, Sir, 1868-1957, donor; S. H. Lazarus (Firm); University College, London. Library Services. Edinburgh : E. & S. Livingstone
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectzoology, bookyear1901
