CHAP. IV] THE GENERAL ANATOMY OF THE TARSII 115 



In regard to the commissures, sufficient note has been taken 

 already of the corpus callosum. The anterior commissure is 

 relatively large, and the dorsal commissure (psalterium) is not so 

 diffused as in the other Primates. The representative of the 

 sulcus suprasylvius has been mentioned already. Other impres- 

 sions on the hemisphere are the fissura hippocampi, together 

 with the representatives of the sulcus calcarinus and sulcus 

 paracalcarinus (on the mesial aspect). (Cf. Fig. 63 and refer- 

 ences : fh. fissura hippocampi, sc. sulcus calcarinus. spc. sulcus 

 paracalcarinus. src. sulcus retrocalcarinus.) 



The cerebellum approaches the form characteristic of that 

 organ in the Insectivora, more nearly in Tarsius than in any 

 other of the Primates. Yet the relatively higher degree of folding 

 in the cerebellar cortex, and the more massive " middle lobe " in 

 Tarsius, shew that this form has advanced already beyond the 

 lowlier stage presented by the Insectivora. 



The hypophysis or pituitary body of Tarsius consists of a 

 median non-glandular portion with two lateral lobules, which 

 are glandular. The glandular parts are said to lie above the 

 diaphragma sellae turcicae. The distinction of a median iobe 

 from two lateral lobules is characteristic of Reptiles. And so 

 far as is known, the Primates alone among Mammals retain this 

 feature. For other details, the memoir by Bolk 1 should be 

 consulted. 



In the preceding notes reference has been made to distinctive 

 characters of the brain which are indicative of a primitive type of 

 conformation. Again, certain features are seen to be associated 

 with special developments, such as that of the eyes. Lastly, the 

 absolute size of Tarsius must be taken into account. The smooth- 

 surfaced neopallium might seem capable of interpretation by an 

 appeal to this factor alone. Yet since the Lemurs fortunately 

 include certain representatives similar in bulk to Tarsius, that 

 interpretation is shewn to be inadequate, and the neopallium 

 of Tarsius is seen to possess the character of smoothness in a 

 degree inappropriate to even Lemurine rank. On the other hand, 

 the fissuration of the cerebellum demands a similar comparison. 



1 Konink. Akad. ran Wet. Amsterdam, Dec. 24, 1910. 



8—2 



