KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 58. N:0 2. 101 



The hairs on the lower lip are in a corresponding manner directed towards its upper 

 margin, where the hairy covering ceases just as abruptly as on the upper lip. In addition 

 to the normal fur of these parts there are to be seen a greet number of long black bristles 

 with undoubtedly sensory function. These attain their strongest development on the 

 chin and lower lip, but they are numerous on the upper lip as well (conf. the fig. 9). 



The nostrils are partly hairy within at their borders. 



With regard to colour and pattern this animal has been so f ully described especially 

 by Fraipont in his great monograph 1 that there is no need to comment further upon 

 this. The dorsal måne, or crest extends in these young animals from the nape to the 

 tall , but the hairs, of which it is composed, are considerably coarser on the f ore-quarters 

 than above the sacral region. j, 



The strueture of the upper lip and snout region of these Okapi calves, as describ- 

 ed above, is very interesting at it illustrates in a very clear manner a stage of develop- 

 ment which is intermediate between the more primitive condition f ound in the Camelidoi 

 with their divided upper lip on one hand, and the various stages of a more or less 

 developed muffle which among the Cavicornia reaches its eulmen in the Bovince. The 

 mode of development is not difficult to understand. The cleft lip of the Camelidce repres- 

 ents a primitive stage, which is repeated in the ontogeny of other Ruminantia. In the 

 adult stage of the latter, however, the lateral portions of the upper lip have j oined 

 mesially in front and grown together. The above described vertical groove in the upper 

 lip of the Okapi calves represents the remnants of this seem, or line of coalescence. 2 

 The inner side of the lip is, of course, lined with a coiitinuation of the mucous covering 

 of the mouth cavity, while the outer surface is protected by the ordinary skin. When 

 in the foetal stage the lateral halves of the upper lips have grown forward so as to meet 

 each other mesially, and the concrescence begins, the line of junction may get a some- 

 what variable situation in relation to the different coverings of the inner and outer sur- 

 faces of the lip. If the line of junction is situatcd just where both tissues meet the 

 result will be that the whole anterior surface of the upper lip is covered with skin which 

 develops hair just as the skin else where, and thus no naked rhinarium is formed as is 

 the case in the Giraffe, Reindeer, Muskox etc. If, however, the mucous lining of the 

 mouth has grown forward so much that the junction of the lateral halves of the lip fall 

 inside the anterior limit of this mucous tissue, the result will be something similar to the 

 condition described above in the Okapi calves, viz. a bare mucous strip along the line 

 of concrescence. As has been mentioned, this bare strip derived from, and forming a 

 remnant of the mucous lining of the mouth cavity is a little broadcr at its upper end, that 

 is just in the inner angle of the cleft between the lateral portions of the lip. It appears 

 thus as if the mucous covering of the inside had a stronger tendency to grow out just 

 there than along the edges below. If this has happened, and, accordingly, when the 

 cleft in the lip is closed, only a portion of mucous tissue has remained exposed at the 

 upper end of the seem, the result will be a small naked rhinarium, isolated far from the 



1 Ann. du Musée du Congo. Zool., Ser. III, T. 1, Bruxelles 1907. 



2 A homologous, although somewhat different groove in the upper lip is, of course, also found among the 

 Sheep, several Antolopes etc. 



