CHAP. XVII.] THE BRAIN OF QUADRUMANA. 



291 



spending fissures in any Lemur (fig. 103) in which they 

 are present. 



The Howler, like the Marmoset and the Squirrel 

 Monkey, is a New World form. The former, in fact, 

 is the largest of the 

 series, and is usually 

 supposed to belong 

 to the highest group 

 of these American 

 Monkeys. Its brain, 

 however, is very 

 poorly developed (fig, 

 109), and, consider- 

 ing its size, possesses 

 very few surface 

 markings. It is re- 

 markable chiefly for 

 the very small size of 



the Occipital, and the FIG. HO. Brain of the Mangabey (Cercopithecus 



r, -I -t -I -I , /. (ethiops), upper aspect. (Vogt. ) F, Frontal ; P, P4rie- 



levelOpmer J OI tal . and 0> occipital Lobes. L, Great Longitudinal 



the Temporal LobeS. Fissure; R, Fissure of Rolando ; V, External Perpen- 



. dicular Fissure ; K, Operoulum. A, A, Ascending 



In Connection With Frontal ; ai, a2, as, First, Second, and Third Tiers of 



fhp VPW mnnll fWi Frontal Convolutions. B, B, Ascending Parietal ; b\ 



J " fra, First and Second Tiers of Parietal Convolutions. 



pital Lobes, Flower * d 1 , t 2 , First and Second Tiers of Occipital Convolu- 



haS noted an almost ^ Tnis simple nomenclature for the Convolutions is 



Complete absence Of tbat of R - Wagner, excepting that A, and B, are 



V TTI j i T T named by him Anterior and Posterior Central Con- 



the .External and In- volutions. Though it is a terminology which is by 



Perpendicular no means without merit, it has not been commonly 

 adopted.) 



Fissures. The brain 



of the Howler Monkey is also remarkable for the extreme 

 backward extension of the Sylvian Fissures (F, F), each of 

 which almost reaches the upper and inner border of its 

 corresponding hemisphere. 



* "Proceed, of Zoolog. Soc." 1864, p. 335, PL xxi*. 



U 2 



