46 EINAR LONNBISRG, MAMMALS COLLECTED IN CENTEAL AFRICA. 



widely from these two species. As P. hatesi is described as »ruf ous almost red- mahogany » 

 it is also very different in colour. In a specimen from Mukimbungu, Lower Congo, which 

 I regard to be P. Vatesi, the bristle hairs are black, unlike those in the new species. 

 P. faustus which Thomas has originally described' from olrneti Bompona, R. Maringa, 

 Central Congo » and quite recently^ also mentioned from Medje and Poko, Upper Congo, 

 is also provided with a very short tail, )>shorter than usual)), viz. 38 mm. With regard to 

 the colour P. faustus reminds about the present species by the presence of a olarge number 

 of hoary-tipped hairs intermingled with the general fur on the body behind the shoulders » 



. )>0f the thin outer hairs projecting beyond the wool-hairs perhaps half are 



blackish and half hoary-tipped. » This partial resemblance cannot, however, lead to 

 identification with this Potto from Masisi as the molars of both species are so widely differ- 

 ent. Thomas writes regarding P. faustus about this: »anterior molar {m}) smaller than 

 m^; m' unusually large, little smaller than m^ and fully as large as m^ Small lower 

 premolars low, not exceeding m^ in height* — — . In Abehenius's Potto m' is a little 

 smaller than m^, but much larger than m' (cf. below), and small lower premolars 

 plainly exceeding mj in height. 



Dimensions of Abrhenius's Potto: Head and body (skin) 395 mm; tail 70 mm; 

 hind foot 76 mm. 



Skull: 



Upper length, occiput to tip of nasals 62,8 mm. 



Basal length 60 » 



Condyloincisive length 64 » 



Least interorbital width JO » 



Zygomatic breadth 45 5 „ 



Length of nasals (uncertain, suture obsolete) 16 » 



Palate length 25 3 » 



Breadth of brain-case 3I 5 „ 



Upper cheek teeth series 18 » 



Molars only 9 „ 



Transverse diameter of m' 3 7 » 



» » i> m' 3 8 » 



' » » m' 3 2, 



The length of m' and m' is practically the same or about 3,5 mm., but the inner heel 

 of m^ is a little narrower than that of m\ The length of m' is about 2,3 mm. 



Length of lover jaw 45 ^^ 



Lower series of cheek-teeth 15 5 » 



Molars only jq ^^ 



The formula of m= should thus be for this species 2,3 x 3,2, while it is for P. faustus 

 3,4 X 4,7 according to Thomas (1. c. p. 427). 



De Winton has not published any cranial measurements of his P. batesi, and the 

 figures quoted by Elliot for the type of this species are unfortunately very uncertain 



1 Ann. & Mag. Hist., Ser. 8, Vol. VI.'p. 426—427, 1910. 

 ' » » » » » » 1) XVI p. 467, 1915. 



