. Outlines of zoology. rtilaginous skeleton andan associated gland. The brain.—The brain (see p. 483) has the followingparts:— I. The fused cerebral hemispheres or prosencephalon, with anervous roof, and without ventricles. cartilage (^.) forming the lower jaw; and the hyo-mandibular(^) which suspends the jaws to the skull. A little fartherback are seen the five branchial arches and the anterior-hyoidarch ; ,f the fifth hypobranchial; ^ the vertebral the right is seen the skeleton of the paired fins, at the leftthe surface of the skin with the sensory tubes (-r.^.); JC, t
. Outlines of zoology. rtilaginous skeleton andan associated gland. The brain.—The brain (see p. 483) has the followingparts:— I. The fused cerebral hemispheres or prosencephalon, with anervous roof, and without ventricles. cartilage (^.) forming the lower jaw; and the hyo-mandibular(^) which suspends the jaws to the skull. A little fartherback are seen the five branchial arches and the anterior-hyoidarch ; ,f the fifth hypobranchial; ^ the vertebral the right is seen the skeleton of the paired fins, at the leftthe surface of the skin with the sensory tubes (-r.^.); JC, thescapular region of the shoulder-girdle, with the scapularfontanelle; c, the coracoid region; ^ the-anterior basalcartilage or pro-pterygium ; ^ the meso-pterygium ; ^the meta-pterygium—all three bear joirited radials, while a few,as shown here, articulate directly with the shoulder-girdle ;pu.^ pubic bar of pelvic girdle ; st.^ stomach; *., spiral valveof intestine. 538 FISCES—/<7SB£ Fig, 283.—Dissection of nerves of skate. CH., Cerebral hemispheres; , optic thalatni ; OL., opticlobes ; M., medulla; 4 V., posterior part of cerebellum, coverinf; CRANIAL NERVES. 539 2. The thalamencephalon or region of the optic thalami, with a: thread-like pineal body above, infundibulum and pituitarybody below, thinly roofed third ventricle within. 3. The mesencephalon or mid-brain, with the optic lobes above, the crura cerebri below, the iter passing between. 4. The cerebellum, with an anterior and a posterior lobe, both marked by ridges and grooves.;. The medulla oblongata, with thin vascular roof, with dorso-lateral extensions called restiform region beneath the thalamencephalon bears—(o) two ovoid inferiorlobes ; (fi) the infundibulum, which carries the pituitary body; and (c) athin-walled three-lobed saccus vasculosus, situated between the pituitarybody and the inferior lobes. Cranial nerves.^—Owing to the flat form of the skateand
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Keywords: ., bookcentury1900, bookdecade1910, bookidcu3192, booksubjectzoology
