370 PHYSIOLOGICAL SERIES. 



In this particular brain the orbital sulctis appears to be 

 almost, if not completely, aborted. 



The right cerebral hemisphere has been dissected so as 

 to expose the hippocampus (major) as a vertical column. 

 Behind and above its upper end is the obverse of the 

 calcarine sulcus, i.e. the calcar avis (so-called "hippo- 

 campus minor"). Nothing points the contrast between 

 Lemurs and Apes so forcibly as a comparison of these struc- 

 tures with those exposed in the brain of Hapale (D. 553). 

 Figures 210 and 211 represent the condition of this speci- 

 men before the dissection was made. 



There is no posterior horn of the ventricle in the Lemur, 

 and the dissection shown in fig. 213 was effected only by 

 separating from the surface of the eminence labelled 

 "calcar" a mass of adherent medullary matter. 



The features of most of the other parts of the brain 

 resemble, like those of Daubentonia, the type which prevails 

 in such forms as the Edentata, Rodentia, Insectivora. and 

 Chiroptera. 0. C. 1337 A. 



T. Ziohen, Arch. f. Psych., Bd. xxviii. 1896, p. ii:'.. 



D, 534. The brain of a Black-faced Lemur (Lemur nigrifrons). 



In this brain the lateral and postlateral sulci ar<> united 

 to form the complete intraparietal sulcus. The anterior 

 extremity of this sulcus is almost (and in the left hemi- 

 sphere quite) confluent with the sulcus rectus. 



The anterior rhinal fissure is faintly indicated, and ex- 

 ternal to it there is a small representative of the orbital 

 (presylvian) sulcus. A small sulcus makes its appearance 

 between the orbital sulcus and the Sylvian fissure in the 

 brain of some Lemurs. It probably represents the fronto- 

 orbital sulcus of the Apes and the diagonal sulcus of other 

 mammals. 



A comparison of the brains of a number of Lemurs shows 

 a series of short sulci in the interval between the dorsal 

 ends of the Sylvian (suj.ra-ylvian) and parallel (postsvlvian) 

 sulci. They may be joined to either of these sulci, and add 

 further testimony to their original connection a< a single 

 supravlvian arc, as in Daubentonia and most non-Primate 





