KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 58. NIO 2. 73 



The difference in the cranial measurements of these two female specimens, which 

 with regard to colour are so similar as possible, is very peculiar. It would be only natural 

 that the dimensions of the molars were somewhat smaller in the older specimen (n:o 152) 

 in which these teeth are more worn than in the younger (n:o 151), but the difference 

 appears in this case far too great, if it is considered that in the oldest, small -toothed specimen 

 the inner cusps of the upper molars are not yet obsolete by wearing. Another absolute 

 proof that the different size of the molar series is not only due to difference in age is of- 

 fered by the fact that thelength of the upper molar series of two other specimens (n:o 155 

 & 158) the same kind only measures 104 mm., although the specimens in question are 

 so young that the inner cusps hardly are worn at all, and the molar series thus absolutely 

 not shortened by wearing. The different length of the molar series becomes by these 

 facts of distinctive value. The upper incisors are also very much broader and stouter 

 in the specimen (n:ol51) with the larger molars so that the combined breadth of both 

 incisors just above the cutting edge amounts to 6 mm., while in the other specimen (n:o 152 ) 

 it is 4,8 mm. In the latter they have the usual chisel-shape, but in the former they are 

 much more transversely worn off , so that the edge is blunt. This latter fact may be due 

 to individually different food, or gnawing on different material (conf. below). This 

 specimen with large teeth has also a very thick preorbital portion of the, skull the trans- 

 verse diameter of the premaxillary region being 13 mm. which is much more than in any 

 other of the present specimens. In the other female skull, the measurements of which 

 are recorded above, the same dimension is 11 mm. The height of the skull at the anterior 

 end of the palatal foramina is resp. 8,8 and 7,2 mm. In connection with the large teeth 

 the musculature of the jaws must be well developed which also produces a very broad 

 and heavy zygomatic arch. The antero-posterior length of the zygomatic plate measures 

 7,6 mm., while the same dimension in the small-toothed specimen is 6,3 mm. The posterior 

 margin of the palate is in the small-toothed specimen more evenly rounded, but in the 

 large-toothed somewhat angular or notehed. 



These differences in cranial structure and dimensions between these two Criceto- 

 mys skulls are so great, that it appears quite impossible to refer them to one and the 

 same race in spite of the facts that they have been collected at the same place, and 

 that the skins are so alike in colour, the only difference readily perceptible being that 

 the white spöt on the upper lip is a little smaller in the big-toothed specimen. The 

 white terminal portion of the tail is also shorter in the same, but it is not excluded that 

 the tail has been mutilated in lifetime. 



Osgood has suggested 1 that »the small-toothed forms of West-Africa are distinct 

 from the large-toothed ones of East and South Central Africa». This is a conclusion 

 drawn from the fact that C. g. emini (a large-toothed form) is found at the same locality 

 as C. g. dichrurus (a small-toothed form) in Northern Congo. 



The question is now whethcr the present large-toothed animal can be referred to 

 C. g. emini, or not. To judge from Wroughton's short description, the hairs of C. g. 

 emini are »greyish white, with apical third brown». This is certainly a quite different 

 colour than the one possessed by the present specimen. The cranial dimensions are also 



1 Ann. & Mag. Nat. Hist. (8) Vol. V, 1910, p. 281. 

 K. Sv. Vet. Akad. Handl. Band 58. N:o 2 10 



