200 ?HILOSOPHICAL TRANSACTIONS. [anNO 16QS. 



the same time, by inflation I distended the bladder of urine,, and the uterine 

 parts too ; viz. The vaginae, the uteri, and the cornua. So that in the skin here, 

 there was only one foramen for the exit of the faeces, the urine, and the foetus. 



I have had no opportunity of dissecting a male possum ; and, indeed, of any 

 other than this single subject : for had I, I might have been more exact in some 

 particulars ; nor is it scarcely possible, to observe all in one. 



The Skeleton. — The head, from the end of the occiput to the extremity of 

 the nares, was 4a inches long ; of which the rostrum or snout measured 3 

 inches ; and just where the snout and the cranium met, the bones were so 

 pinched in at the sides, that here it was very narrow ; and indeed, in proportion 

 to the bulk of the animal, this was the least cranium that ever I met with in 

 a quadruped. On the forehead, the snout was an inch broad, having on each 

 side, a protuberance jetting out. There was a large suture just in the middle, 

 which divided the upper bones of the nares lengthwise, and though they ran 

 slender towards the extremity of the nares ; yet these bones, towards the fore- 

 head, spread into a triangular figure, and as they are joined together, form a 

 rhomboid, or a lozenge. There was a remarkable ridge, like a crest, that ran 

 the length of the cranium, from the forehead to the occiput, just in the middle ; 

 where the sutura sagittalis is in other skulls. This ridge, for distinction sake, 

 I shall call protuberantia ossea longitudinalis ; and it jetted out from the 

 cranium above ^ of an inch : just at its' upper edge was a seam like a suture ; 

 so that, though these bones are so well united together, as to appear but one 

 entire body, yet in the foetus they are doubtless separable, and are two. And 

 this I rather think, because in the upper part of the cranium I could not find 

 any sutures at all. So likewise, those other ridges in the extremity of the 

 occiput, which I shall call protuberantiae osseae laterales, which rising on each 

 side from the processus styloides, ascend obliquely up the hinder part of the 

 occiput, and just in the middle at the top are joined with the longitudinal 

 ridge, I have described. These ridges, though as deep as the first, yet were 

 not standing so upright but projected rather like a pent-house over this hinder 

 part of the cranium ; by both which ridges, the cranium is so well guarded and 

 defended, that it is almost impossible the skull should be any ways cracked or 

 broken. Something like these ridges, but not nearly so large, I have observed 

 in the skull of a vveazel. 



And not only the brain, but the eyes likewise are very well guarded and de- 

 fended, by the os zygomaticum ; which is very broad and strong ; being in the 

 broadest place above i of an inch, and in the narrowest J- inch, and very tiiick 

 on its under edge ; but at its upper, growing thin and sharp. But for the 

 greater strengthening this bone, which is formed by a process from the os 

 temporum, and another from the maxilla superior, where they meet, they over- 



