. Outlines of zoology. Zoology. NERVOUS SYSTEM. 605 The hind-limb consists of a short stout femur, a tibia to which the proximal tarsals (astragalus and os calcis) are fused (forming a tibio-tarsus), an incomplete fibula joined to the tibia, three metatarsals fused to one another and to the distal tarsals (forming the tarso-metatarsus), a free first metatarsal, and, finally, the four toes. The first, turned backwards, has two phalanges, the second three, the third four, and the fourth five. Nervous system.—In contrast to the brain of crocodiles and other Reptiles, the brain of the pigeon and o
. Outlines of zoology. Zoology. NERVOUS SYSTEM. 605 The hind-limb consists of a short stout femur, a tibia to which the proximal tarsals (astragalus and os calcis) are fused (forming a tibio-tarsus), an incomplete fibula joined to the tibia, three metatarsals fused to one another and to the distal tarsals (forming the tarso-metatarsus), a free first metatarsal, and, finally, the four toes. The first, turned backwards, has two phalanges, the second three, the third four, and the fourth five. Nervous system.—In contrast to the brain of crocodiles and other Reptiles, the brain of the pigeon and other Birds fills the cranial cavity. The cerebral hemispheres are large and smooth. Their roof is thin, their main mass consists of the large cor- pora striata which bulge into the ventricles. They meet the cerebellum and throw the solid optic lobes to the sides. The olfactory lobes are very small (cf. deficient sense of smell). Between the cerebral hemispheres and the cerebellum, the pineal body rises to the surface, and a slight posterior separa- tion of the hemispheres will disclose the region of the optic thalami. The cerebellum is ridged transversely and divided into a , median lobe and two small lateral flocculi. r The curvature of the brain is well marked in the adult, thus the medulla is quite hidden by, and descends almost vertically from, F,G; r^s—Bones V , ,, of hind-limb of. the cerebellum. eagle. J., Femur; , tibio-tarsus; /l>., fibula; «., ankle- joint ; mt., tarso- metatarsus; mf., first metatarsal (free). There are as usual twelve cranial nerves. In connection with the spinal cord, the brachial plexus of nerves to the forearm, and the sacral plexus to the leg, should be noticed. In the lumbar region the halves of the cords diverge for a short distance, forming a wide space—the rhomboidal sinus —roofed only by membrane. The cervical part of the sympathetic nervous system is double on each side. Sense organs.—The sense of smell is not well develo
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Keywords: ., bookauthorth, bookcentury1800, bookdecade1890, booksubjectzoology
