MOEPHOLOOY OF THE BEAIX IX THE MAMMALIA. 345 



I'crodictieus (Royal College of Surgeons, no. 2i)5) reveals a pattern identiciil with that 

 seen in the actual brain, which T have just described. 



In the little brain of Loris (jracHis the olfactory parts closely resemble those of the 

 other two genera of Lorisinge. The upper ends of the supra- and postsylvian sulci 

 approach very near to one another on the left hemisphere ; on the right hemisphere the 

 former is prolonged into a hook surrounding the upper end of the postsylvian. There is 

 a simple arcuate lateral sulcus and a small postlateral. There is a small oblique orbital 

 sulcus ; and a shallow furrow placed far forward may represent the coronal sulcus. 



so. -'P- 



Litns r/r<icif<s. 

 Lateral aspect of the left cerebral hemispljerc. Nat. size. 



There is also a small inferior temporal sulcus on the left hemisphere, as in the brain of 

 Nyeticehus. On the mesial surface the typical calcarine group and shallow intercalary 

 and collateral sulci are found. 



Beddard examined the brain in two specimens of Lo7-is f/raci I is, and stated that "there 

 are only three fissures plainly visible — the Sylvian, the angular [lateral], and the antero- 

 temporal [postsylvian] " (Proc. Zool. Soc. 1895, p. 145). [His representation of the 

 brain (fig. 3) is, however, so studded with innumerable spider-like figures as to be 

 ([uite unintelligible.] In one of his specimens there was a separate postlateral [his 

 " parieto-occipital "] sulcus on one hemisphere. 



Gervais's illustration (Journ. de Zoologie, t. i. pi. 2. fig. 2) is useful as a demon- 

 stration of the actual size and shape of the brain in Zoi-is ; but Beddard's criticism 

 of his representation of the sulci is quite justified. Among the Lemurs it is possible, if 

 the investigator has studied the effect of brain-form on the cranial wall in some members 

 of the Order, to foi-m a very good idea of the configuration of the actual brain from an 

 examination of the brain-case. But Gervais has not exercised sufficient caution in the 

 representation of the plaster casts, and gives an altogether erroneous idea of the 

 configuration of the brain. 



Ziehen's account of the brain in this genus was based upon the specimen in the Royal 

 College of Surgeons and another specimen of his own. He represents the lateral aspect 

 of the left hemisphere (Arch. f. Psychiat. xxviii. iig. G, p. yos). The Sylvian fissure, 

 orbital sulcus, a very short postsylvian sulcus and a " Scheitelstiick " above it, a lateral 

 and po.stlateral sulcus are all shown ; but in addition there is a transverse sulcus labelled e, 

 not present in Beddard's specimens nor in that in the College of Surgeons. The letter 

 e is used by Ziehen to designate the central sulcus in Pcrodiclicus, and both the sulcus 

 wiiich I call/ and that designated .r in Nijcllcehns. 



51* 



