1908.] ANTECHINOMYS AND OTHER MARSUPIALS. 569 



the presence of any folds in the gut, but gives measurements of 

 the lengths of the several parts of the gut. 



The late Sir William Flower * by implication makes the same 

 statement; for he remarks of the alimentary tract of the Opossum 

 {Didelphys virginiana) that " the colon forms a single arch and 

 then passes directly down to the pelvis ; but being very loosely 

 attached by mesentery it is very movable." 



None of these writers, however t, with the exception of 

 Sir Richard Owen, I'efers to the fact that among the Marsupialia 

 there are two gi'ades in the complication of the alimentary tract 

 to be met with. That author says of Dasyurus niaculatus — " The 

 mesenteiy was one continuous duplicature of the peritoneum 

 extending from the pylorus to the end of the colon as in the 

 Reptilia." 



It appears to me that by this phraseology is indicated an 

 intestine like that of Antechinomys described in the present 

 paper %, comparable to an early stage in the development of the 

 alimentary tract of man before the hinder part of the gut has 

 been folded over the anterior part. In his Treatise on Com- 

 parative Anatomy the " reptilian " condition of the gut in 

 certain Marsupials is more, plainly stated. 



These two stages in the development of the intestine are 

 ^figured in Flower's Lectures on the organs of digestion in the 

 Mammalia already referred to and in any textbook of human 

 anatomy. It is obvious that the conditions obtaining in Antechi- 

 nomys represent the first stage persistently retained. There 

 are not many positive facts which lead to the supposition that 

 any other Marsupial shows the same. The only figures of the 

 entire alimentary tract of a series of Marsupials known to me 

 are those of Mitchell already referred to, and of Klaatsch §. But 

 there is no indication here of difierentiation between the lower 

 and higher types in the direction referred to. Klaatsch, indeed, 

 figvires Dasyurus viverrinus as not possessing the "reptilian" 

 form of gut, since it possesses the cavo-duodenal ligament. I can 

 quite confirm him fi-om an examination of D. maugcei. 



That this simple form of gut is not due merely to its shortness 

 and to the mechanical difiiculty implied by a folding over, is 

 proved by the occurrence of the same type in animals belonging 

 to other orders of mammals. In Centetes ecaudatus, for example, 

 among the Insectivora, there is precisely the same type. The 

 continuous mesentery of the gut is nowhere folded over, and the 

 whole intestine is arranged exactly on the plan of that of 

 Antechinomys, though it is much longer. Dr. Mitchell's figure 

 of Centetes might at first sight appear to bear out my statement. 

 But if this figure be compared, e.g., with that of Phcdangista 



* In his Lectures on the Alimentary System of Mammals reported in Med. 

 Times and Gazette, 1872. 



t Nor is the fact adverted to by Cunningham in his description of the gut of the 

 Thylacine, &c., Rep. Zool. Challenger, vol. v. 



X Supra, p. 562. 



§ Morph. Jahrb. xviii. 1893, p. 622, fig. 2, p. 664, fig. 10, pi. xxii. fig. 7. 



