166 MESSRS. SCHAFER AND WILLIAMS ON THE [Jan. 18, 



gardens of the Society. This latter has been described (P. Z. S. 

 1875, p. 48) by Prof. A. H. Garrod, the Prosector to the Society, to 

 whom we are indebted for the opportunity of examining the organ 

 in question in these animals. Our original object was simply to 

 record in general terms the differences in microscopic structure 

 presented by those parts of the membrane which have a different 

 appearance to the naked eye ; but since, in spite of recent researches, 

 our knowledge of the minute structure of the gastric mucous mem- 

 brane is still confessedly imperfect, it became obvious that it would 

 be necessary to enter upon a minute examination of the several 

 parts ; especially as they present very well-marked differences, and, 

 in some cases, peculiarities of structure which tend to elucidate 

 points yet in dispute with regard to the gastric mucous membrane 

 of the higher Mammalia and of Man. 



As is well known, the stomach i§, in the Kangaroo, a long saccu- 

 lated organ not uulike the human colon ; and the sacculations, as in 

 that, are due to the presence of three longitudinal bands of plain 

 muscular fibre, situate on the exterior underneath the serous mem- 

 brane and shorter than the rest of the gastric wall, so that this is 

 bulged out at intervals into sacculi separated by constrictions or 

 inward folds of the membranous wall. One of the three bands is 

 placed below along the greater curvature ; and it is on either side of 

 this that the sacculi are most marked ; there are none at the lesser 

 curvature, nor is the pyloric extremity sacculated at any part of 

 its circumference. Besides the inwardly projecting folds between 

 the sacculi, and which involve all the coats of the stomach, the 

 mucous membrane shows the rugse ordinarily met with in a stomach 

 not completely distended, and produced by contraction of the mus- 

 cular coat. There are also in certain parts more minute folds, 

 which would, no doubt, be effaced by complete distention of the 

 organ, and which are probably due to a similar contraction of the 

 muscular layer of the mucous membrane (muscularis mucosce). 



In the diagrams of the two stomachs which are here given, and in 

 the accompanying general description, they are for convenience' sake 

 treated as if they were more or less straight organs extending across 

 the body from left to right as in the human subject, whereas in 

 reality they are twisted upon themselves. A detailed description of 

 the form of the marsupial stomach and its relations to other parts is, 

 of course, foreign to the subject of the present paper, and must be 

 sought for in recognized treatises on comparative anatomy *. 



* The following are the dimensions of the organs as they appear after pre- 

 servation in spirit : — 



Dorcopais Macropus 



luctuosa. gic/tu/fi us. 



ft. in. ft. in. 



Length along lesser curvature 10 18 



Length along greater curvature, the sacculations 



not being taken into account I 7 2 5 



Length along greater eurv;ttutv, reckoning in the 



sacculations 2 10 5 



Greatest circular measurement 7 7 



In both cases the stomachs were filled with partially digested food. 



