18/6. j MUCOUS MEMBRANE IN KANGAROOS. 169 



orifice are only slightly marked in the stomach of Macropus. The 

 second region (B) has a greater extent in Macropus giganteus than 

 in Dorcopsis. It occupies all the rest of the inner surface of the 

 stomach except (as in Dorcopsis) a circular patch (C) about 3 

 inches in diameter, situate at the pyloric fundus, and not marked off 

 from the rest by any well-defined naked-eye appearances except the 

 great thickness of the mucous membrane. But microscopical exa- 

 mination shows that the glands of this patch present material dif- 

 ferences from those of the rest of the stomach, whilst resembling 

 those of the corresponding part of the Dorcopsis stomach ; so that this 

 patch is to be taken as representing the third region in Macropus also. 

 The tract n, moreover, which passes in Dorcopsis over the upper 

 part of the stomach in this place, is also represented in Macropus. 

 The second region may be said to commence at the extreme end of 

 the cardiac fundus, where its mucous membrane lines the pouch (/?) 

 above referred to as not being covered by the hard gullet-epithelium ; 

 from here it passes to the right, along the greater curvature of the 

 stomach, gradually narrowing at first, so that opposite the oesophagus 

 it forms a strip only about | of an inch wide, bounded on either 

 side by the epithelium of the first region, but subsequently becoming 

 gradually wider until it extends continuously round the organ. 



In both animals the raucous membrane of the second region has 

 here and there insular elevations flattened on the surface and beset all 

 over with small rounded eminences, each with a little pit at its summit 

 as if made with the point of a pin. These elevated patches vary in 

 size, but seem to have a fairly regular distribution (Diagrams 1 and 

 2, /, I). Thus in both animals there is a large triangular patch on 

 each wall of the stomach, the base of which is close to the third region 

 of the mucous membrane, while the apex of the triangle extends 

 upwards and to the left towards the lesser curvature. From near 

 the apex a chain of smaller and more circular patches is continued 

 for some distance parallel to the line of demarcation between the first 

 and second regions — in Dorcopsis, in fact, as far as the second region 

 extends. As the result of microscopical examination clearly shows, 

 these elevations are owing to accumulations of lymphoid tissue in and 

 beneath the mucous membrane ; and they may therefore be termed 

 "lymphoid patches." They are in many respects analogous to 

 Peyer's patches of the small intestine. 



Microscopical Characters of the Mucous Membrane. 



The results of the microscopical examination of the several regions 

 correspond for the most part in both animals (as might indeed have 

 been expected in genera so closely allied) ; so that the same description 

 will apply to both. We shall afterwards take the opportunity of 

 pointing out any special peculiarity which may obtain in either. The 

 figures, which have been taken indiscriminately, some from the one 

 animal and some from the other, will, for the most part, serve to 

 illustrate the structure of the corresponding parts in both. 



The Mucous Membrane of the First Region. — This is covered with 

 a coating of dense stratified epithelium (Plate VIII. fig. 1, S) con« 



