54 



EDENTATA. 



Fig. 39. 



Stomach of the Sloth. 



of the stomach by a semilunar fold. The 

 cardia opens very far towards the right side, 

 leaving a very large pouch, and enters a canal 

 which proceeds along the right side of the 

 first stomach, giving off from its right margin 

 a broad process, which separates the pouch 

 of the stomach from the other cavity, which 

 lies between the pouch and the appendix 

 before mentioned. Thus the first stomach 

 is divided into three cavities. The canal 

 already described turns from the left towards 

 the right, and enters the second stomach by 

 a narrow opening. The second stomach is 

 of a slender form, much smaller than the 

 former ; its parietes are very thin for the first 

 half of its length, but much thickened towards 

 the pylorus ; and the two portions are sepa- 

 rated by a semilunar fold. Again, the first 

 portion of this second stomach is itself partially 

 divided by a beautifully indented fold, the 

 dentated processes of which are directed 

 towards the pylorus. There is also attached 

 to the second stomach a small cul-de-sac, 

 which lies between two similar ones connected 

 with the first stomach, the internal surface of 

 all of which appears to be glandular. In the 

 AT the appendix to the second stomach is much 

 longer, and divided into three chambers by 

 two membranous partitions. 



The whole of this structure, and especially 

 the canal which extends from the cardia to the 

 second stomach, indicates a very remarkable 

 relation to that of the ruminants, and is 

 evidently intended for the digestion of vege- 

 table substances only. 



In the Edentata proper the stomach is, as 

 may be expected, far more simple. In the 

 Myrmecophaga didactyla it is of a globular 

 form, and simple. In the Manis pentadactyla 

 or Pangolin, it is internally divided by a fold 

 into two cavities, of which the left, analogous 

 to the paunch, is thin, and the pyloric, or true 

 digestive portion, much thicker. 



The intestinal canal does not present the 

 same striking distinctions between the large 

 and small intestines which are observed in 

 most other mammifera. There are in the 

 Ant-eaters two coecal appendices, which may 

 be considered as forming the boundary between 

 the two portions, of which the posterior is 

 very much shorter than the anterior. It is 

 remarkable that the entrance to these small 

 coeca is so contracted as wholly to prevent 



the passage of any faeces into them. In the 

 Manis longicauda there is not the vestige of a 

 coecum. In the Orycteropus it is short and 

 oval. In the Tardigrade^ the AT for example, 

 the large intestine is at once distinguished 

 from the small by its sudden enlargement, and 

 at their junction is found a slight fold, which 

 partially separates them. 



The liver offers but few peculiarities of 

 consequence in a physiological point of view. 

 In the Ant-eaters, the Armadillos, and the 

 Orycterope, it consists of three lobes. In 

 the former the hepatic duct joins the cystic 

 at a considerable distance from the neck of 

 the gall-bladder, and, as in the Armadillo, at 

 a very acute angle. 



Organs of circulation. In a paper in the 

 Philosophical Transactions, Sir A. Carlisle 

 described a very remarkable peculiarity of the 

 arrangement of the arteries of the limbs in 

 several slow-moving animals, of which number 

 were the Bradypus tridactylus and Bradypus 

 didactylus. It appears that the axillary and 

 iliac arteries, on entering the upper and lower 

 limbs, are suddenly divided into a number of 

 cylinders of equal size, which occasionally 

 anastomose with each other. They are ex- 

 clusively distributed in the muscles. Those 

 of the other parts of the body, and even 

 those of the limbs which supply the bones, 

 &c. do not deviate from the usual mode of 

 distribution. In the former species no less 

 than forty-two of these cylinders were counted 

 on the superficies of the brachial fasciculus, 

 and there were probably not less than twenty 

 concealed in the middle. In the second 

 species they were less numerous, and deviated 

 from the usual form. This difference in the 

 two species is perfectly consistent with what 

 is known of their habits ; for there can be no 

 doubt that the peculiarity has reference to the 

 slowness of motion of these animals, in which 

 character the AT far exceeds the Unau. " The 

 effect of this peculiar disposition of the arteries, 

 in the limbs of these slow-moving quadrupeds, 

 will be that of retarding the velocity of the 

 blood. It is well known, and has been 

 explained by various writers, that the blood 

 moves quicker in the arteries near the heart 

 than in the remote branches ; and also, that 

 fluids move more rapidly through tubes which 

 branch off suddenly from large trunks than 

 if they had been propelled for a considerable 

 distance through small-sized cylinders; be- 

 sides the frequent communications in the 

 cylinders of the Bradypus tridactylus must 

 produce eddies which will retard the progress 

 of the fluid. From these and a variety of 

 other facts, it will appear that one effect on 

 the animal economy, connected with this ar- 

 rangement of vessels, must be that of di- 

 minishing the velocity of blood passing into 

 the muscles of the limbs. It may be difficult 

 to determine whether the slow movement of 

 the blood sent to these muscles be a subor- 

 dinate convenience to other primary causes of 

 their slow contraction, or whether it be of 

 itself the immediate and principal cause." 

 The integument in the Manis as well as in 



