•i 



KiNAE Lönnberg, 



numerous than in the sheep. The pyloric tract is to an extent of 7 

 cm. entirely free from folds, but the shorter folds of the greater cur- 

 vature disappear already al twice that distance from the pylorus. 



From the condition of the dorsal division of the paunch and 

 that of the psalterium as described above it is evident that the ven- 

 tricle of the Black-buck represents a stage of reduction when compa- 

 red with that of the sheep. The cause why such a reduction has 

 taken place must lie in an altered diet. If a ruminant begins to feed 

 on more nourishing food than before the reservoir formed by the 

 paunch may be lessened without detrimental effect, and if the food is 

 softer and more easily crushed by the teeth the grinding action of the 

 psalterium is not so important and this organ may therefore be re- 

 duced in size. Unfortunately 1 do not know anything about the diet of 

 the Black-buck, but it lives in a climate which allows the animal to 

 obtain green herbs all the vear round and it may therefore have the 

 opportunity to choose tender leaves and sprouts. Brehm says that 

 it feeds on »Gräsern und saftigen Kräutern», but it is uncertain how 

 much such a statement may be relied upon. There is, however, a 

 different condition of life for the Black-buck than for the wild sheep 

 and other ruminants which live in a temperate climate so that they 

 at least during the winter must feed on dry plants, bark of twigs and 

 similar matter, harder to digest, more difficult to grind and less nou- 

 rishing. In the latter case a large paunch and a powerful psalterium 

 is well needed. The variability of the psalterium has already been 

 observed by previous authors and in the following will be offered 

 further proofs of this. Garrod 1 ) remarks that the organ in question 

 is minute in »Nannotragus» (Ourebia) and Gephalophus. Boas 2 ) found 

 the psalterium of Cephalophus maxwelli to be only 2 cm. in length, but 

 in the same animal the abomasus measured 11 — 12 cm. The same 

 species was also among those examined previously by Garrod (1. c.|. 

 Boas terms the psalterium of the said animal rudimentary. In the 

 Tragulids the psalterium is perfectly rudimentary, as is well known. 

 Boas puts this in connection with the small size of the animals. He 

 says that it is probable that such small ruminants as those mentioned 

 above do not choose the coarsest food and that therefore the food 

 »schon beim Wiederkäuen so fein gekaut worden, dass eine wieder- 



1 ) Proc. Zool. Soc. London 1877. 



2 ) Morph. Jahrb. XVI. Leipzig 1890. Conf. also the statements below in another 

 shapter of this paper. 



