212 



RODENTIA. 



their hind-feet forwards under their belly, and their fore-feet obliquely 

 forwards. 



The oesophagus is continued about two inches below the diaphragm. 

 The stomach is much as in the guinea-pig. The duodenum passes to 

 the right, and down the right side behind, and adhering to the ascend- 

 ing part of the caecum ; then winds round the root of the mesentery 

 and gets upon the left of it, where it becomes loose. From the pylorus 

 to behind the mesentery, it describes nearly part of a circle ; and in 

 this course it is so firmly attached to the parts, that it can hardly be 

 said to have a mesoduodenum. The ileum, before it enters the colon, 

 is attached to the caecum for nearly a foot, by a thin membrane, which 

 appears to be a continuation of the mesentery. This membrane is 

 longest where the ileum 1 begins to be attached, and then becomes 

 narrower, till at last the ileum adheres to the caecum. The beginning 

 of the caecum is on the left side ; it is vastly large : it passes to the 

 right, crossing the pelvis, then passes up the right to the liver; it 

 adheres to the duodenum, then makes a turn across the abdomen 

 towards the left, close to the stomach, and terminates in the blind end 

 before it has got to the left side : these two last turns are something 

 like the human colon. It is becoming gradually smaller to the end. 

 At the end it has three ligaments, but on the greater length it has five. 

 The colon is pretty large at the beginning, but soon becomes small : 

 it is reflected to the right in the fore-part of the caecum, connected to 

 it by a thin membrane, which becomes narrower and narrower, till at 

 last the colon adheres to the caecum, follows its turns nearly to the tip, 

 is then bent back upon itself for some inches, is again bent upon itself 

 for the same length, after which it passes to the left and becomes 

 loose ; as it passes down the left side it has a pretty long mesocolon, 

 and is there thrown into several convolutions, especially as it passes 

 over the left iliacus intemus muscle, like the sigmoid flexure of the 

 colon of the human. The faeces are soft, like dough 2 . 



The liver is divided into four lobes. The two on the left side are the 



1 [In a capybara dissected at the Zoological Gardens, about an inch from the end 

 of the ileum the muscular fibres were very strongly marked, and seemed especially 

 so round one spot, so as to cause a comparison of it to the ball of the thumb, there 

 being a projection. This had probably been where the umbilical vesicle was attached, 

 which therefore is no doubt largely developed as in other Rodentia, taking a great 

 share in the uterine development of the animal. The placenta, therefore, has less to 

 perform, and we found indeed scarcely any trace of unibiucal vein at the anterior 

 margin of the suspensory ligament, which was situated as usual : a large baboon which 

 was examined at the same time showed well the contrast with the rodent in their 

 manner of development by the size of the suspensory ligament.] 



- [Home, Comp. Anat. i. p. 454 ('Le Cabiai').] 



