260 PHYSIOLOGICAL SERIES. 



There is a very deep, long, transverse, crucial sulcus 

 (fig. 133) ; and in some cases, if it be opened up, a small 

 indubitable precrucial sulcus is present. The crucial sulcus 

 is joined by the intercalary to the deep calcarine sulrus, 

 as is commonly the case in the Dogs (fig. 134). Then- 

 nre, in many Hyaenas, numerous irregular accessory post- 

 calcarine sulci the irregular forerunners of the n-tro- 

 calcarine and collateral sulci of the human brain. There 

 is also a well-developed marginal (" suprasplenial '") sulcus. 

 The genual sulcus in some cases proceeds upward to join 

 the precmcial. 0. C. 1325 Ea. 



D. 316. The brain of a Hyama (Hycena hycena). 0. C. 132. 



D. 317. The brain of a Hyaena (Hycena hycena), ( $ ). 



0.0. 1325 K<*. 



D. 318. The brain of a Hyaena (Hycena hycena), ( ? ) . 



O.C. 1325 Eft. 



D. 319. A brain labelled "Hyaena/' Although much larger than 

 the other specimens of the Hyaena's brain, this specimen 

 presents similar features. 



The " Sylvian fissure/' however, is more open and tli<> 

 sulcus which emerges and indents its posterior lip perhaps 

 the "posterior terminal sulcus" of Holl is unusually 

 well pronounced. 0. ( ' 1 



D. 320. A cast of the cranial cavity of a Spotted Hyaena (// 

 crocuta) . 



This shows the size and shape of the olfactory hulU, 

 which are distorted in the specimens of the brains them- 

 selves. Note that the open condition of the pseud osylvian 

 sulcus is natural, as it is seen in the cast. 



Gervais, Nouv. Arch. d. Mus., t. vi. 1870, j. 1-J.~>. 



D. 321. The brain of a Proteles cristatus, (<$). 



This closely resembles the brain of the Hyaena. 



It is of interest to note a rctrocalcarinc sulcus extending 



