378 



THE KABB1T. 



the hinder ends of the hemispheres thicken still more, to form 

 the corpora striata (Fig. 155, BI), a pair of prominent swellings, 

 lying in front and to the outer sides of the optic thalami, BU, 

 and separated from these by well-marked grooves. 



The hippocampus major (Fig. 152, H) is a prominent curved 

 ridge, projecting into the lateral ventricle, and extending round 

 into its descending cornu : it is really an inwardly projecting 



F.M 



C.H 



V.P 



IV' 



FIG. 153. A longitudinal and vertical section of the brain of an adult llabbit, 

 taken in the median plane. (From Marshall and Hurst.) 



A, pituitary body. AC, anterior commissure. AF, anterior pillar of the t'omix. 

 seen in the wall of the third ventricle. C, cerebellum. CA, corpus albirans. CC, 

 corpus callosum. CH, inner surface of left cerebral hemisphere. F, body of the fornix. 

 FM, foramen of Monro. G-, velum interpositum. I, infundibumm. MC, middle 

 commissure. N", anterior lobe of corpora quadrigemina, or 'nates.' O : .olfactory lobe. 

 OC, optic chiiisnia. OK", left optic nerve. P, pineal body. PC, posterior commissure. 

 PV, pons Varolii. T, posterior lobe of corpora quadrigemina, or ' testis.' VA, velum 

 medulliv anterius, or valve of Vieussens. VP, velum medulla posterius. 



Ill, tliird ventricle. IV, fourth ventricle. V, fifth ventricle. 



fold of the wall of the hemisphere, formed by a deep groove on 

 the surface of its inner wall. 



The choroid plexus of the lateral ventricle (Fig. 155, x) is 

 a somewhat similar, but much thinner fold of the inner wall of 

 each hemisphere, between the two layers of which blood-vessels, 

 XD, pass in freely. It lies immediately below the hippocampal fold. 



The commissural bands between the two hemispheres are 

 very characteristic structures in Mammals, in which they attain 

 a much higher development than in. other Vertebrates. The 

 most important of these are the corpus callosum, the fornix, and 



