KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 58. N:0 2. 7 



specimens, witliout which it would ha ve been impossible to form any definite opinion 

 in such a difficult matter. In some instances a similar variation has been reported upon 

 before. For instance, Lorenz von Liburnau has written abont the colour variation 

 among the red Co/o&ws-monkeys which he has named C. variabilis, and which variation 

 also is to be seen in this collection. It is also well known to every mammologist, who 

 has worked with African mammals, that among certain kinds of mammals the colour, 

 and to some extent even the pattern, may be subjected to a considerable variation, as 

 for instance is the case among Genets and Bushbucks. But this is not a very common 

 occurrence, and in most cases the skulls offer very good and fairly constant characteristics. 

 In the following memoir I have been able to prove that the variation of the cranial 

 dimensions and other characteristics among some mammals from the Central African 

 Lake district is extraordinarily great. Such facts as are described below concerning 

 the Chimpanzees, some of the Guenons, the Giant Råts (Cricetomys) etc. offer undoub- 

 tedly a valuable contribution to the knowledge about the individual variation among the 

 mammals. It is among other things of interest to find that the cranial characteristics of 

 some Primates are so very variable. 



Of some of the species represented in the collection there are specimens of different 

 age and sex so that a fairly good general view of the ratio of growth and development 

 with increasing age can be obtained, and this is recorded by means of tables of measure- 

 ments and descriptive notes. To a certain extent it is also illustrated by the accompany- 

 ing plates. 



The capacity of the brain cavity has also been measured, especially for the Primates, 

 but also for some of the other species. Now and then morphological notes have been 

 added. It would have been fortunate, if this part of the work could have been further 

 extended, but as the author has been very heavily pressed with much labour of different 

 kinds it has been connected with many difficulties to find time to get it ready even to 

 its present form. 



Gorilla beringei mikenensis n. subsp. 



N:o 164, 1 old male 14th of May 1914 in the bamboo-forest on the volcano Mikeno, Vi- 



runga mountains (Pl. I, fig. 1). 

 N:o 165, 1 semiadult male, last molar not quite fully developed, occipital and sagittal 



crests not developed, the same locality and date. 

 N:o 166, 1 young male with milk-dentition and the f irst molar, the same locality and date. 

 N:o 167, 1 adult female, the same locality and date. 



N:o 168, 1 young female with milk-dentition and first molar, the same locality and date. 

 N:o 39, 1 young female, second molar just cutting the gum, in the bamboo-forest at the 



foot of the volcano Mikeno, 27th of Dec. 1913 (Pl. I, fig. 2). 

 N:o 40, 1 young male, second molar developed, the same locality and date as n:o 39 



(Pl. I, fig. 2). 



The naked parts of all are black. The scattered hairs of the upper lip of the old 

 male are black. The hairs on the crown are black, but partly with subbasal paler rings, 



