KUNGL. SV. VET. AKADBMIENS HANDLINGAR. BAND 49. :S(:0 7. 31 



to the raphe on the inner side of this lip and on the peduncle of the mushroom-like 

 appendage as described above. 



The presence of the frenum is of importance because Owen (1. c. p. 50) has 

 stated that there is no frenum between the prepuce and the penis in the Indian 

 Rhinoceros. 



Since it now has been shown that the members of Rhinocerotidce probably all of 

 them have a penis with a similar structure it remains to find out whether the same 

 organ of the two other families of Perissodactyla can be derived from such a type, 

 or at least from an ancestral type which can be assumed as common to all three. 



Owen states that »in the Sumatran Tapir the base of the glans has an upper 

 lobe as well as one on each side, beyond which it is continued forward contracting, 

 but terminates in a truncate surface on the middle of which the urethra opens ».^ 

 The lateral of these lobes can no doubt be homologised with those of the Rhino- 

 ceroses, and this must be regarded as an important correspondence. The truncate 

 shape of the anterior end is also a Ukeness, although the Tapir has no mushroom- 

 like appendage in front. This may have become reduced in the ancestors of the 

 Tapir, or independently developed in the Rhinoceroses. 



The homologisation of the different parts of this organ of the Rhinoceroses, 

 and of the Indian Tapir is still more facilitated by Poelman's description^ and figure 

 of the conditions found in the latter species. The author quoted says: »Le gland 

 — — — son extremite libre est plutot aplatie, et a la partie inferieure de celle-ci, 

 au fond d'une fossette, se trouve I'orifice de I'uretre. » This »fossette» is no doubt 

 to be regarded as homologous with the apical groove of the glans of the Rhinoceroses, 

 although the appendage is missing. Poelman's figure (1. c. PI. II) presents »trois 



especes de cretes ou de bour relets aplatis — ». These are evidently the same as 



those mentioned by Owen, as quoted above. An examination of Poelman's figure 

 (1. c. PI. II) convinces one that the two lateral of these lobes evidently must be 

 quite homologous with those in a corresponding situation on the male organ of the 

 Rhinoceroses.' 



In the Horse there are no lobes on the male organ, but such lobes may have 

 been present and become reduced already among the ancestors of the Horse. But 

 the corpus penis of the Horse ends, according to Ellenbergbr and Baum,* with 

 three apices in front. The middle one of these is long and pointed, and it serves 

 to support the glans. The lateral ones are termed »kurz und stumpf». The hypo- 

 these is near at hand that these lateral apices may have formerly stood in connection 

 with lateral lobes of the penis of such a kind as those found in the Rhinoceroses. 



1 Mem. de I'Acad. R. Belgique. T. XXVH, p. 17 & PL H. 



^ These lateral lobes of the male organ appear to be developed in comparatively late ontogenetical stages, 

 for Paekee remarks (Proc. Zool. Soc. London 1882, p. 773) that be did not find them in a young Indian Tapir 

 This is very remarkable as the presence of such lobes must be phylogenetically very old when two families like 

 Ehinocerotidce and Tapiridm are provided with such. I have seen myself the lobes in question strongly developed 

 in a living Tapir. 



* Anatomy of Vertebrates IE, p. 664. 



* Handbuch d. vergl. Anat. d. Haustiere. ll:te Aufl., p. 553. 



