178 PHYSIOLOGICAL SERIES. 



instead of the customary single sulcus, which is the so- 

 called " Sylvian fissure." On the right hemisphere of this 

 hrain a third sulcua, which may be distinguished as 0, 

 shares the representation of the pseudosylvian furrow. The 

 sulcus c is divided into two parts, but neither of these, nor 

 the sulcus B joins the so-called suprasylvian. The latter is 

 not joined to the orbital sulcus on the right side. 



In each hemisphere there are two horizontal prorcan sulci 

 in front of the orbital sulcus. There is also an extensive 

 vertical sulcus parallel to the sulcus B, near the posterior 

 margin of the hemisphere. 



(Ziehen describes a brain of Macropus rufus. Jena. 

 Denkschr., Bd. vi. 1897, p. 54.) 



D. 212. The brain and the upper portion of the spinal cord of a 

 Giant Kangaroo (Macropus giganteus) . 



This is the largest brain found in any existing Marsupial, 

 although the extinct forms Thylacoleo and Diprotodon 

 possessed brains of much greater size. 



In this specimen the large olfactory bulbs are missing. 

 but the size and shape of these parts of the brain are well 

 shown in the casts of the cranial cavity (D. 215). 



The orbital (presylvian) sulcus and the sulci A and B all 

 spring from the rhinal fissure. The sulcus B on the left 

 side joins the suprasylvian sulcus, and the latter extcml> 

 almost as far forward as the orbital (presylvian). A 

 prorean sulcus is present. On the right side there is an 

 addition.il sulcus between the sulci A and B, and the or Ml a 1 

 sulcus is small. 



It is a strange fact that the " pant medial " sulcus (compare 

 fig. 58), which is such a characteristic feature of all other 

 representatives of the Macropodidae, is lacking in this, tlie 

 largest member of the family. 



Behind the sulcus B there an- a number of small sulci. 

 which on the whole assume a vertical (transverse) direction. 



The characteristic features of the base of the mammalian 

 brain are exceedingly clearly demonstrated in this specimen 

 (fig. 57). Note especially the thin-walled pouch of the 

 infundibulum, from which the pituitary body has been 

 torn away. 



