34 



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

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

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

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

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

 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 -vvhales. It consists of three lobes, ■with a small Spigelian lobu- 

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

 lobes is the smallest, and presents a quadrate figure, \vith 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, -vvhich 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 fuiidiis ; it re- 

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

 a junction of the cystic ■vvith the hepatie duct, \vith or without he- 

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

 \vhich pierce its cervix obliąuely, 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 vesica. 

 The cervix contracts gradually into the cystic duct, which exclusively 

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

 t\vo 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 

 ■vvide vence hepaticce 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, -vvhich is not perforated by that vein. 



" In the Dugong No. 2, the pancreas, which was situated belo\v 

 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 to\vards the 

 duodenum. Its secretion is carried from the component lobules by 

 from t\venty to thirty ducts, each about two lines in diameter, to a 

 very \vide common excretory canal, vvhich terminates below, but on 

 the šame 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, ■VN'hich measured four inches 

 in length ; but in the other specimens this alone -vvas present. 



CiRCULATING SySTEM. 



" Ali the three specimens presented the šame remarkable extent of 

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

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



* See Novi Commenlaru Acad. Scient. Petrop. t. ū. 1751. 



