34 



well-developed gall-bladder. Daubenton found a gall-bladder in the 

 Manatee ; but the jjresence of this organ is not constant in the her- 

 bivorous Cetacea, for in the Northern Manatee {Stellerus borealis, 

 Cuv.), according to Steller*, the gall-bladder is wanting, and its 

 absence seems to be compensated by the enormous width of the duc- 

 tus communis choledochus, which would admit the five fingers united. 

 The liver in the Dugong is more flattened, and more divided than in 

 the true whales. It consists of three lobes, with a small Spigelian lohu- 

 lus continued from the root of the left lobe. The middle of the three 

 lobes is the smallest, and presents a quadrate figure, with its free 

 margin projecting forwards, notched for the reception of the suspen- 

 sory and round ligament, and, in one of the specimens, obtusely 

 bifurcate ; it overhangs, as it were, the gall-bladder, which is lodged 

 in the middle of its concave or under surface. The gall-bladder was 

 four inches in length and one inch in diameter at its fundus ; it re- 

 ceives the bile in a peculiar manner ; not, as in other Mammalia, by 

 a junction of the cystic with the hepatic duct, with or without he- 

 pato-cystic ducts, but by two large hepato-cystic ducts exclusively, 

 which pierce its cervix obliquely, just as the ureters convey the renal 

 secretion to the urinary bladder. The orifices of the above ducts are 

 half an inch apart, and three inches distant from the fundus vesicce. 

 The cervix contracts gradually into the cystic duct, which exclusively 

 conveys the bile to the intestine. It was six inches in length, and 

 two lines in diameter; but became dilated just before it entered the 

 duodenum, and, as it passed between the coats of that gut, its lining 

 membrane was developed into reticulate folds, presenting the only 

 appearance of a valvular structure in the course of the duct. Three 

 wide vena hepaticee from the left side, and one on the right side of 

 the liver, join the inferior cava at the upper and posterior edge of the 

 liver, which is not perforated by that vein. 



" In the Dugong No. 2, the pancreas, which was situated below 

 and behind the pyloric compartment of the stomach, was seven inches 

 in length ; thick and obtuse at the splenic or left end, where its di- 

 ameter was two inches, and gradually becoming smaller towards the 

 duodenum. Its secretion is carried from the component lobules by 

 from twenty to thirty ducts, each about two lines in diameter, to a 

 very wide common excretory canal, which terminates below, but on 

 the same prominence, with the cystic duct ; at a much greater rela- 

 tive distance from the pylorus than in the true Cetacea. In one of 

 the Dugongs dissected by me I found two small accessory spleens, 

 in addition to the larger rounded one, which measured four inches 

 in length ; but in the other specimens this alone was present. 



Circulating System. 



" All the three specimens presented the same remarkable extent of 

 separation of the two ventricles of the heart which Raffles and Home 

 have described in the individuals dissected by them, and which Riip- 



* See Novi Co/nmenlarii Acad. Scient. Petrop. t. it 17ril. 



