224 PHYSIOLOGICAL SERIES. 



The chief interest of this brain is the wide separation ol 

 tin- so-called *' Sylvian fissure " and the suprasylvian sulcns 

 in the right hemisphere. The condition almost always 

 found in Myrmecophaga is seen on the left hemisphere. 

 There the so-called " Sylvian fissure " and the suprasylvian 

 sulcus have become confluent so as to form a long, deep 

 sulcus extending almost as far as the lateral sulcus. The 

 postsylvian sulcus is not joined to the suprasylvian clement. 



This confluence of these two elements to form a Sylvio. 

 suprasylvian complex is of great interest, because there* are 

 many reasons for believing that a similar fusion takes place 

 in the Primates. If this be so, the " Sylvio-suprasylvian M 

 complex of the Anteater is the nearest approach to the 

 condition of the true Sylvian fissure of the Primates. 



Now such a confluence of these two sulci may be regarded 

 as the normal condition in the Great Anteater. The interest 

 of this fact is enhanced when it is recalled that the calcarine 

 sulcus is separated from the intercalary another Primate 

 feature. 0. C. 1323 K. 



Presented by the Zoological Son, t if. 



Elliot Smith, Trans. Linn. Soc. vol. vii. 1899, p. 



D. 282. The brain of a Great Anteater (Myrmecophaga julata) , in 

 which the right hemisphere has been separated from the 

 rest of the brain. (Figs. 96, 97, 98, 99.) 



The sulci in this brain are exceedingly interesting win MI 

 compared with those of the above specimen (D. 281). 



The Sylvio-suprasylvian complex approaches so near to 

 the upper extremity of the postsylvian, as to afford a 

 striking resemblance to the suprasylvian arc on the right 

 hemisphere of specimen D. 281; thus it further con firn is 

 the suprasylvian nature of the upper part of the"Sylvi<- 

 suprusylvian " sulcus. 



There is no diagonal sulcus, such as is seen in the 

 preceding specimen. There is a very short posterior 

 sylvian sulcus on the right hemisphere and none on the left. 



On the left hemisphere the orbital or presylvian sul-us 

 opens into the anterior rhinal fissure. On the right hemi- 

 sphere it does not do so; it is also quite independent 

 of the small prorean sulcus on this side. 



