312 N. w. ingallS 



behind the first annectant gyrus. This is the new branch of Cun- 

 ningham (1. c, '92, p. 225) and the occipital ramus has now the 

 appearance of ending with a terminal bifurcation, of which the 

 two limbs are quite different morphological value since the lateral 

 limb is a continuation of the original fissure and is, as we shall see, 

 alone of significance as a limiting fissure. 



The sulcus praelunatus, occipitalis lateralis, is common and 

 may be conceived as arising from one of the furrows which sep- 

 arate the more lateral annectant gyri, possibly between the third 

 and fourth, the extreme development of one of these gyri might 

 give rise to a gyrus translunatus. 



All that remains of the inferior occipital of the Cercopithecidae 

 is a small shallow furrow or a few fragments, which, as above 

 stated, we shall refer to as the sulcus sublunatus. It may be en- 

 tirely wanting or again fairly well developed as it is in the Gibbon. 

 The sulcus occipitalis inferior of the Simiidae and of man presents 

 a much more difficult problem: it might be brought into relation 

 with the Querfurche of Zuckerkandl or wdth fissures in the con- 

 tinuation of, or representing the descending branch of, the su- 

 perior temporal. Three principal varieties are found, in which it 

 is dependent or confluent in front with the middle temporal or 

 with the temporo-occipital (inferior temporal). These relations 

 as also the position of its posterior extremity, which may be found 

 on the lateral or tentorial aspect of the hemisphere, are intimately 

 associated with the position of the lunate and its associated areas. 

 In a brain in which the lunate stops some distance above the mar- 

 gin of the hemisphere the inferior occipital sulcus will be on the 

 lateral surface and often united with the middle temporal, while 

 in the opposite condition it is on the tentorial surface and contin- 

 uous with the temporo-occipital, but in any case its posterior end 

 may reach the tentorial surface. 



Before we proceed farther in our discussion it will be neces- 

 sary to define what we mean by the sulcus lunatus, for it is with 

 the region immediately in front of this sulcus that we are espe- 

 cially concerned. Any definition which involves homology, as 

 does this one, must be the most comprehensive possible without 

 being in any wise indefinite or equivocal. By comprehensive 



