NERVOUS SYSTEM. VERTBBRATA. 463 



operculum cannot be seen.] The sulcus rectus (inferior 

 frontal) is already developed. The central is a simple 

 (and single) straight linear sulcus. 



The intraparietal system is represented hy short shallow 

 sulci representing the raraus postcentralis intrrior and 

 ramus horizontalis, and very faintly-marked depressions 

 representing the ramus postcentralis superior and ran.n, 

 occipitalis. 



The parallel is a very short sulcus. 0. C. 1341 o. 



Presented by S. G. S/iattocI . 



D. J. Cunningham, Royal Irish Acad. Memoirs, Nos. 6 

 &7 (1892). 



D. 682. The left hemisphere of a human foetus shortly before 

 birth. 



D. 683. The brain of a Microcephalic male Idiot, twenty-two 

 years of age. He was 4 feet 8 J inches in height. 



When first removed from the body, the brain weighed 

 12 \ ounces (355 grms.). (In adult human males of a stature 

 of 65 inches and under, the weight of the brain averages 

 46'95 ounces [1315 grms.].) The extreme length of the 

 median curve of the hemispheres was 120 mm. The cere- 

 bellum projected 20 mm. beyond the occipital lobe. 



After preservation in spirit the median curve of the frontal 

 lobe from its anterior pole to the fissure of Rolando measures 

 76 mm., the parietal lobe 37 mm., and the occipital lobe 

 from the parieto-occipital fissure to its posterior pole 7 nun.: 

 there is therefore a marked deficiency of the occipital lobes, 

 which do not nearly cover the cerebellum. The anterior 

 inferior portion of the central lobe or island of Reil is ex- 

 posed on the surface of the hemisphere, and is only slightly 

 below the level of the frontal cortex. The exposure of this 

 part of the island of Reil is due to the deficiency of the 

 frontal and orbital opercula which cover the central lobe in 

 the healthy adult human brain. The fronto-orbital sulcus 

 bounds the exposed part of the insula anteriorly ; above, it 

 is limited by the superior limiting sulcus or lower 

 border of the third frontal convolution. On the right side 



