BY R. BROOM. 613 



organ, shows some of the Diprotodont characters, «.</., the carti- 

 lages being considerably apart, and the organ having a large gland 

 duct entering it from above. 



PJiascolomys mitche/li, Owen, (half grown specimen). In this 

 specimen, which may be taken as tlie adult type, we ha^e a great 

 similarity in many ways to the condition in Phascolarctus. Here 

 there is, however, but a very feeble development of the outer 

 nasal-floor cartilage, and in this resembling Macropus. 



In PI. XLViii. fig. 3 we have a section through the posterior part 

 of the very large papilla — a portion of the papillary cartilage 

 being still seen. At this plane the septum dips considerably 

 below the level of the nasal floor, and has by the side of the dee2> 

 portion a descending plate from the nasal-floor cartilage, or 

 possibly rather an enormousl}' thickened inner end of the cartilage. 

 In fig. 4 this lai'ge inner pnvt of the nasal-floor cartilage becomes 

 still more developed and extends down into the hollow formed 

 between the premaxillary and its palatine process, about to become 

 detached in section. Below the bon}' isthmus is seen the very 

 long and oblique naso-palatine canal. I-n tig. 5 the palatine 

 process is detached from the premaxilla, and in the gap between 

 is a distinct descending plate which almost meets the naso-palatine 

 canal and rests on the palatine process. The cartilage is excavated 

 in the middle for the anterior part of the organ, but its roof is 

 entire and united with the feeljle outer portion of the naso- 

 palatine canal. Fig. 6 shows the anterior part of the organ 

 situated in the hollow of Jacobson's cartilage and opening into 

 the naso-palatine canal exactly as in Macropus. Here the outer 

 part of the roof cartilage has become detached from the outer 

 nasal-floor cartilage. A little behind this plane the lower part 

 of Jacobson's cartilage passes up and forms a complete tube for 

 the organ as in Phascolarctus. The palatine process is situated 

 very much as in Macropus, but more inferiorly. 



The organ is fairl}'- developed, and more than lialf fills the 

 cartilaginous tube. At its upper inner angle it receives a number 

 of gland ducts, the glands Ivino; at the inner side of the upper 

 41 



