KUNOL. SV. VET. AKADEMIENS HANDLINGAR. BAND 58. N:0 2. 15 



Through correspondence with Matschie I have also had the pleasure of receiving 

 information concerning the shape of the jugale in 0. beringei. In the latter is the posterior 

 angle between the horizontal ramus of jugale and its rdmus frontalis almost right, while 

 it is much smaller in the adult Mikeno Gorilla. (Cf. the figure plate III.) As the same 

 angle in the younger Mikeno Gorillas comes nearer to a right angle than in the old, G. 

 beringei represents in this respect a more juvenile stage. 



According to Matschie there is an angular ridge between the inner surface of the 

 lateral wall of the orbit and the facial or front surface of ramus frontalis of jugale, and these 

 two surfaces stand in a right angle to each other.^ In the Mikeno Gorillas (and in this 

 respect young and old are alike) on the other hand the interior surface of the orbit is 

 quite smoothly rounded off and passes gradually into the semicylindrical facial surface 

 of ramus frontalis of jugale (PL II, fig. 1). 0. graueri Matschie appears to more nearly 

 resemble the Mikeno Gorilla in this latter respect, but otherwise these two differ very 

 much from each other as will be shown further below. 



With regard to the colour of the fur the adult Mikeno Gorilla J* differs from G. 

 beringei by the absence of wed » as well at the tips as at the bases of the hairs of the head, 

 neck, and legs. From G. graueri the Mikeno Gorilla differs by its greater dimensions 

 in many respects. Although the total length of the skull of the former is almost similar, 

 or 312,5 mm, its condylobasal length is maximum 223 mm. against 255 mm in the Mikeno 

 Gorilla, and in a similar way the basal length is resp. 201 to maximum 210, and 231 mm; 

 the width of 2)Zaw'J*m jiitcAaZe resp. 151, maximum 154, and 165, mm.; the palate length 

 resp. 128 (maximum), and 137 mm., the distance from palatal arch to occipital crest resp. 

 187 and 194 mm. 



I am indebted to Professor Matschie for several of these measurements of G. 

 graueri, which have not been published before. They are based on a material of three 

 adult specimens. The same author has at the same time kindly communicated that in 

 G. graueri »die Reihe der Schneidezahne im bleibenden Gebisse hochstens 4,2 cm. breit; 

 die Gelenkhocker am Hinterhaupte bei den J" 2,4 cm. bei den $ 2,i em. lang». In the 

 Mikeno Gorilla the series of upper incisors has a length of 4,5 cm. basally, and the length 

 of Condyli occipitales measiires in J* 2,32 cm., and in ? 1,85 cm. 



Considering the differences recorded above and the fact that the Gorillas are rather 

 stationary and now live isolated in the upper parts of the mountain forests, chiefly in the 

 bamboo region — at least this is the case with the Mikeno Gorilla — it appears probable 

 that this isolation has brought about a certain differentiation between the different tribes. 

 Therefore, I cannot identify this Gorilla with any of the known eastern forms, but regard 

 it, as a separate subspecies which may be called Gorilla beringei mikenensis. 



The capacity of the brain-cavity of these Gorillas from Mikeno has been measured 

 by means of hemp seed, since fissura ofbitalis etc. has been closed with a little cotton, 

 and the following results have been obtained: 



The young female with milk-dentition (n:o 168) 417 ccm. 



The adult female (n:o 167) 435 » 



i>die Aussenwand der Orbita steht zur Fazialflaohe des Eamus im rechten Winkel>) (Matschie). 



