220 DIGESTION. [CHAP. xxv. 



examined by ourselves, which measured from snout to tail seven inches, the 

 intestinal canal, from pylorus to anus, measured four feet three inches. 



In the Cheiroptera, a very marked distinction exists in the form of the intes- 

 tinal canal between the frugivorous and insectivorous genera. In the former, 

 as in Pteropus, it presents numerous coils, and is in length seven times that of 

 the body the coecum is absent. In the latter, the canal is extremely short, 

 bearing to the length of the body the proportion of two or three to one, as in 

 Vespertilio noctula. Much variety exists as regards both the form and length 

 of the intestinal canal in the Edentata. The distinction between large and 

 small intestine is not evident in many of the genera. In the Manis and Bra- 

 dypus, there is no trace of a ccecum ; on the other hand, the two-toed ant- 

 eater (Myrmecophaga didactyla) has, according to Daubenton and Meckel, two 

 small and narrow co3cal appendages, resembling those of birds, situated at the 

 confines of the two portions of the intestine ; the orifices of these co3ca are so 

 small, that the foecal matter cannot find its way into them. Mr. Owen has 

 preserved in the Hunterian collection a specimen from the weazel-headed 

 armadillo (Dasypus mustelinus), of two similar coeca, between which the ileum 

 terminates. The terminal aperture of this intestine is of a slit-like form, and 

 from its position between the co3ca, it admits of being effectually closed by the 

 lateral pressure of the contents of the co3ca.* 



Great length and wide calibre are the characteristics of the intestinal canal 

 in Ruminants, Solipeds, and Pachydermata. In the sheep, which belongs to the 

 ruminant order, the intestine is in length thirty times that of the body, and in 

 a horse, according to a measurement made by us, the intestinal canal was 

 eighty-seven and a half feet in length. There are numerous convolutions of the 

 small intestines in each of these orders, and a large capacious coecum, from 

 which the wide and convoluted colon is continued. In Ruminants, neither the 

 coecum nor the colon is sacculated by longitudinal bands, whilst both the Solipeds 

 and Pachydermata exhibit the sacculated character in a very marked degree, 

 and the bands of longitudinal muscular fibres are very highly developed, ex- 

 tending from the blind extremity of the coecum to the rectum. There is no ileo- 

 coecal valve, properly so called, in these orders, but the passage from the ileum 

 to the coecum (a foot and a half long in the horse) is very much contracted, and 

 its inner membrane thrown into six or eight thick longitudinal folds, which are 

 closely applied to each other, and keep the canal closed. The coecum in each of 

 the orders is very capacious ; in the Euminants, the capacity of this portion 

 of intestine somewhat exceeds that of the fourth stomach according to Meckel. 

 In the Solipeds, the coecum is still more capacious. Meckel asserts that it is 

 capable of containing more than three times as much liquid as the stomach. 

 In Pachydermata, the coecum is shorter and wider than in the other orders : 

 it is, according to Meckel, less capacious than the stomach.t 



The Rodentia have, in general, a very long and convoluted intestinal canal. 

 The small intestine has a mesentery of considerable length ; its calibre is small 

 and pretty uniform throughout, being, however, largest superiorly. In most of 

 the Rodent genera, the coecum is of very great size ; and in some it occupies a 

 large portion of the abdominal cavity ; in the omnivorous rodents, however, as 



* Catalogue of the Hunterian Museum, vol. i., p. 219, 729, A. 

 t See Sir E. Home's plates of the cceca of several mammiferous animals, 

 plates cxiii. et seq, vol. ii. 



