. Outlines of zoology. tiges of femur and tibia. The rounded brain is relatively large, with well-convolutedcerebral hemispheres. As to the alimentary system,—salivary glands are rudi-mentary or absent, the stomach is chambered, the intestinehas rarely a caecum, the liver is but slightly lobed, there isno gall-bladder. The heart is often cleft between the ventricles. Botharteries and veins tend to form retia mirabilia. The larynx is elongated, so that it meets the posteriornares, and forms a continuous canal, down which air passesfrom nostrils to. lungs. The inspiration and expirationoccur at
. Outlines of zoology. tiges of femur and tibia. The rounded brain is relatively large, with well-convolutedcerebral hemispheres. As to the alimentary system,—salivary glands are rudi-mentary or absent, the stomach is chambered, the intestinehas rarely a caecum, the liver is but slightly lobed, there isno gall-bladder. The heart is often cleft between the ventricles. Botharteries and veins tend to form retia mirabilia. The larynx is elongated, so that it meets the posteriornares, and forms a continuous canal, down which air passesfrom nostrils to. lungs. The inspiration and expirationoccur at longer intervals than in terrestrial mammals. Thewater-vapour expelled along with the air from the lungs CETACEA. 769 condenses into a cloud, which is sometimes increased byan accidental puff of spray. The kidneys are lobulated. The testes are are no seminal vesicles. The uterus is placenta is non - deciduate and diffuse. The twomammae lie in depressions beside the genital aperture, and. Fig. 414.—Pelvis and hind-limbof Greenland whale (Balcena).—After , Pelvis; F., femur; T., tibia. the milk is squeezed from special reservoirs into the mouthof the young. Usually a single young one is born at a time,and there are never more than two. All are carnivorous; but, while many feed on smallpelagic animals, other swallow cuttles and fish, and Orcaattacks other Cetaceans and seals. Most are gregarious,and live in schools or herds. 49 [Table, 770 MAMMALIA. CONTRASTS BETWEEN THE TWO SUB-ORDERS OFLIVING CETACEANS Mystacoceti or Bal^noidea,baleen Cetaceans. Odontoceti or ,toothed Cetaceans. The teeth are absorbed before birth. Whalebone or baleen-plates develop asprocesses from the palate. The skull is symmetrical. The nasals roof the anterior nasal pas-sages, which are directed upwardsand forwards. The maxilla does not overlap the orbitalprocess of the frontal; The lachrymal is small, and distinctfrom the jugal. The tympanic is
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Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192, booksubjectzoology
