12 



MR. JAMES JOHXSTOXE OJf THE 



epithelium containing cardiac glands (" progressive development"), 

 and in Manis as due to the restriction of that area(" retrogressive 

 development "). In the first case it is related to the necessity of 

 digestion of an exceeding large amount of food-material ; and 

 in the second to the digestion of a small quaatity of easily 

 assimilated food. 



The terms " gastric gland " of English authors and " grosse 

 Magendriise " employed by the Germans, are alike misnomers. 

 The organ, as both Oppel and Toepfer have pointed out, is not 

 a gland in the sense in which that term is legitimately employed, 

 but a complex evagination of the gastric wall, bearing, in common 

 with the rest of the stomach, true glands ; and as such it does not 

 seem as if its value can be very great as affording any trust- 

 worthy indication of the phylogenetic history of the animal in 

 which it occurs. In the case of two forms like PJiascolarctus 

 and PJiascolomys, known ,^ from other considerations, to be nearly 

 related to each other, the common presence of a " gastric gland " 

 may indeed afford reason for their closer approximation ; and 

 in these animals the organ does seem to be homologous, although 

 in the Koala its structure is more specialized than in the case 

 of the Wombat. But statements as to an organ in the Eodentia 

 resembling the "•gastric gland"' of Marsupialia, and conclusions 

 as to a closer degree of genetic relationship of these two 

 groups, deducible therefrom, in view of the great specialization 

 of the stomach occurring in some Eodents, must, I think, be 

 received with hesitation. 



I am indebted to Prof. G. B. Howes for supplying me with 

 the material reported on, and for kindly furnishing me with 

 many of the worts cited. Part of this investigation was done 

 while I was still a student under him in the Besearch Laboratory 

 of the Rojal College of Science, London. 



Bibliography. 



1. PoRBES, W. A. — " On some points in the Anatomy of the 



Koala {Phascolarctus cinereus).^' Proc. Zool. Soc. London, 

 1881, pp. 180-195. 



2. Plower, W. H. — Lectures on the Comparative Anatomy of 



the Mammalia. Med. Times and Gazette, vol. i. pp. 215-678 

 & vol. ii. pp. 1-345. 1872. 



