162 THE VOYAGE OF H.M.S. CHALLENGER. 



In the Vulpine phalanger, the mesentery of the great intestine is only four inches 

 long, whilst that of the small intestine is five inches long. 



The mesenteric glands are few in number but relatively of large size. 



The caecum has a distinct mesentery which is continued to its extremity, and is an 

 offshoot from the meso-colon. 



The duodenum is completely invested by peritoneum, and there is no demarcation of 

 any kind between it and the jejunum. 



Spleen. — In both Thylacine and Cuscus the spleen is an elongated tongue-like organ 

 completely invested by peritoneum, and placed obliquely in the abdominal cavity. From 

 its outer border a process of spleen substance projects towards the kidney. The splenic 

 vessels, nerves, &c. enter the organ upon its inner surface along the line of the mesenteric 

 attachment. 



Pancreas. — The pancreas is well developed in both the Thylacinus and Cuscus. 

 It consists of a thickened massive right extremity or head from which an elongated 

 process of gland substance projects towards the spleen. The pancreatic duct joins the 

 bile duct before it enters the duodenum. 



Liver. — In describing the liver we shall adopt the admirable nomenclature suggested 

 ten years ago by Professor Flower 1 in his lectures on the Comparative Anatomy of the 

 Organs of Digestion in the Mammalia. In neither animal is there a trace of the " round 

 ligament." This condition is to be associated with the total absence of a fossa ovalis 

 in the heart, and of the ductus arteriosus. 



In the Cuscus the liver is divided into a right and a left segment by a deep fissure 

 which may be termed the umbilical cleft. It cuts the organ almost completely into two, 

 and its significance is shown by its coinciding with the line of the suspensory ligament. 

 The left segment, which is only very slightly smaller than the right, is subdivided by a 

 deep cleft (the left lateral fissure of Flower), into a large "left lateral lobe" and a very small 

 " left central lobe." The right segment also consists of a " right central lobe," and a " right 

 lateral lobe." The latter is very small and insignificant, and the fissure (right lateral 

 fissure) which cuts it off is very deep and almost reaches the attached border of the 

 organ. The right central lobe is the largest of all the subdivisions of the liver. Behind 

 it is hollowed out into a deep ditch or furrow which runs in the antero-posterior direction 

 about its middle. This furrow contains the upper end of the gall bladder and the cystic 

 duct, and extends upwards to the portal fissure ; traced forwards it widens out and at the 

 same time deepens, and finally it becomes a distinct V-shaped cleft in the sharp free 

 margin of the liver which allows the fundus of the gall-bladder to be seen from the 

 front. 



The accessory lobes are both present. The Spigelian lobe is well marked, and is 

 partially sub-divided by shallow clefts into three subsidiary portions. It has a leaf-like 



1 Medical Times and Gazette, vol. i., 1872, p. 292. 



