26 BINAB LONNBEBG, ANATOMICAL NOTES ON EAST AFRICAN MAMMALS. 



csecum (PI. 2, Fig. 2), and the walls of this pocket are partly attached to the ter- 

 minal piece of the ileum on its mesial side. The opening of the ileum is directed 

 obliquely against the colon, but the passage from the caecum to the colon is very 

 effectively occluded by not less than three constrictions which each of them only 

 leave a narrow opening (PJ. 2, Fig. 2). Between these three constrictions the lumen 

 widens very considerably so that wide pockets are formed between the narrow pas- 

 sages. At the latter the mucosa is laid in longitudinal folds by which the lumen is 

 still better closed. These pockets and constrictions correspond to colic haustra which 

 have become more strongly developed and specialised. The colon forms a spiral the 

 coils of which are quite closely connected and pressed to each other (PI. 2, Fig. 1) 

 but which in consequence of the large size of its constituents is very big. From the 

 cgecal tract the colon runs forwards on the left side below the kidney to behind the 

 ventricle. From there it returns backwards on the right side and becomes visible on 

 the (ventral) surface of the spiral near the csecal tract when the first coil is nearly 

 complete. In the second coil the forward ascending limb also soon disappears below 

 other coils* and the only superficially visible portion of this coil as well, is behind, 

 just before the second round is completed. The third and last centripetal coil has 

 an altogether superficial situation. The same is the case with the first and second 

 centrifugal coils (the latter is the most peripheric) but the forward on the right side 

 ascending limb of the third centrifugal coil disappears below the surface and com- 

 pletes its turn with rapidly diminished diameter. A fourth and a fifth centrifugal 

 coils with still smaller diameter encircle the root of the mesentery before the large 

 intestine runs backwards as rectum. From this description and the figure communi- 

 cated (PI. 2, Fig. 1) it may be seen that the colic spiral of the Warthog is flatter 

 and wider than that of Sus and it may be regarded as enlarged and more specialised 

 which also is born out by its structure in details.^ 



The colon of this young Warthog is very strongly sacculated, and the folds 

 between the hauslra very often cut off the greater part of the lumen of the organ. 

 This sacculation is well developed on all the centripetal coils, and also on the three 

 and a half first centrifugal coils. In consequence of this arrangement the contents 

 of the large intestine can be retarded in their passage through the organ and retained 

 as long time as is necessary for the digestive process. 



The dentition of the Warthog is more specialised than in any other member of 

 the family Suidce and adapted to grind coarse vegetable matter. The development 

 of the colon as described above is evidently also an adaptation to the same kind of 

 a diet. As the stomach is comparatively small it is probably of comparatively less 

 importance for the digestion. The small intestine is wide to facilitate the passage of 

 the coarse food-material, but it is not especially elongated. It is thus chiefly entrusted 

 to the colic portion of the intestine to prepare the food in such a way that its di- 



^ if seen from the ventral surface. 



^ I have regarded the point where the star-mark is seen in the Fig. 1 (PI. 2) as the turning point of 

 the spiral, but it is quite a matter of taste to remove this point half a, turn further upward in the figure. Ac- 

 cording to the situation of the coils the turning point appeared, however, to be at the place mentioned. 



