VERTEBRATA. 81 



mice, and shrews which are purely frugivorous, and in sloths, 

 which live on vegetable food, the intestine measures only about 

 three times the length of the body; whilst in the porpoise and seal, 

 which live on animal food, it measures in the former 11 times, and 

 in the latter 28 times the length of the body. But this apparent 

 anomaly is explained by recollecting that the caecum plays a com- 

 pensating part with respect to the other portions of the alimentary 

 canal, indeed the researches of the Heidelberg professors authorise 

 us in believing that it acts the part of a second stomach, and that 

 where the latter is simple, the coecum presents a complex and 

 highly developed condition, and vice versa. Hence by a reference 

 to the highly developed coecnm and vermiform appendix of the 

 rodentia, we are enabled to reconcile their simple form of stomach 

 with their herbivorous food. In the elephant, the small intestine 

 measures 3S feet, the colon and rectum 20£ feet, and the coecum 1£. 

 In the camel, the small intestine is 71 feet, the colon and rectum 

 56, and the coecnm 3. The intestine is 10 times the length of the 

 body in the horse, and 28 times in the sheep. In an ornitho- 

 rhynchus 17£ inches long, the small intestine measured 4 feet 4 

 inches, and the colon and rectum 1 foot 4 inches. In this animal, 

 the rectum, urinary, and genital organs terminate in a cloaca, as in 

 birds and amphibia. 



The solidungulous pachydermata masticate their food before it is 

 swallowed, therefore they do not ruminate, and require but a simple 

 digestive stomach ; but they have the same narrow lengthened form 

 of intestine, and a capacious sacculated coecum and colon. The 

 liver is largest in the cetacea and those animals that dive or burrow ; 

 smaller in the herbivora, and least in the carnivorous tribes. There 

 seems to be no general law for the presence or absence of the gall- 

 bladder in mammalia more than in birds and fishes ; it is for the 

 most part wanting in the herbivorous species, as the deer and 

 the camel ; it is also absent from most of the rodentia and pachy- 

 dermata ; and here the hepatic duct is generally much dilated, as in 

 the horse and elephant. In the otter a similar dilation exists in 

 conjunction with a gall-bladder. It is remarkable that all the 

 mammalia which want this reservoir, except the porpoise, are 

 phytophagous. 



In the course of my dissections during my pupilage at the college, 

 I, together with my esteemed friend, Surgeon Bewley, of Moate, met 

 with a female subject about nine years of age, in which this recep- 

 tacle was absent. I invited the attention of Dr. Houston to this, I 

 believe, unique anomaly, who has prepared and deposited the 

 biliary apparatus in the museum of the college. 



The spleen is long, flat, and attached to the paunch in the rumi- 

 nantia, narrow and lengthened in the carnivora, and in the porpoise 

 it consists of several portions. The pancreas is long, flat, and 

 attached to the right end of the first stomach in the cetacea, in other 

 mammalia it is longer, and often divided into several portions, its 

 8 — g evers 6 



