Material for the Study of Ruminants. 



25 



middle of the dorsal edge. It resembles consequently the same organ 

 of Cervicornia, Giraffa and Ovibos. The ontogenetic development of 

 this species as well as that of Cephalophus ogilbyi proves therefore, 

 that the triangular shape of the spleen is a secondarily aquired cha- 

 racteristic, as I have pointed out before. 



2) A foetus of Cephalophus melanorhoeus <S fr., measuring from 

 the forehead to the anus 114 mm. and from the snout to the occi- 

 put -17 mm. 



The fine bristles above the upper eyelid are beginning to appear 

 in two series. Some bristles on the sides of the lower jaw are also 

 developed and on a prominent wart or cushion on the chin, between 

 the rami of the mandible, four small bristles are developed. Otherwise 

 the specimen is naked. 



The arched row of pores of the anteorbital gland seems to be 

 divided into 23 transversal groups, but the pores are not quite di- 

 stinct yet. 



When the exterior of this foetus is examined the great size of 

 the scrotal sack is one of the most striking features. It measures 

 fully 11 mm. in depth and 8 mm. in anteroposterior direction. The 

 prepuce is also large, protruding about 3 l h mm. and with a trans- 

 versal diameter of equal size. Just in front of the scrotal sack or on 

 a level with its anterior border is, on each side, a single wart about 2 

 mm. in diameter. This is the rudiment which later should have de- 

 veloped into the teats and although there is only one such on either 

 side, each of them has distally an anterior and a posterior small tip 

 thus indicating the future division into two teats (see fig. 14 a). This 

 is important because it indicates that the four teats of Cephaloplni* 

 melanorhoeus are developed from only two rudiments, one on 

 each side, which becomes divided. The warts of this stage are namely 

 »Anlagen» of teats only, not of udder. This is proved by compa- 

 rison with a somewhat later stage in which the division is more pro- 

 nounced and with a still later in which four teats are seen, but no 

 trace of an udder. If the warts of this stage had represented an 

 udder and only the small tips had been the rudiments of teats, it 

 follows that also in a later stage an udder must have been present. 

 But as this is not the case the above statement must be correct, these 

 warts are only rudiments of teats and become later divided into two 

 (compare also next stage). Such a division is of course a rather 

 remarkable fact as it would seem more probable that a smaller number 



Nova Acta Reg. Soc. Sc. Ups. Ser. III. Impr. 1903. . 4 



