374 Proceedings of the 



pubic bones of the pelvic arch, affording support for a marsu- 

 pium or pouch in the female, into which the ovoviviparous off- 

 spring is received at its birth. With the exception of the 

 Thylacinus cynocepJialus, or pouched dog-headed Thylacine 

 of Tasmania, these marsupial bones have been found to be 

 present in both sexes in all the animals of this group yet ex- 

 amined. 



After these and other general remarks on some of the leading 

 points connected with the marsupial group of mammals, Dr 

 M'Bain gave a detailed description of a skull in his possession. 



" This skull was presented to me by an esteemed friend 

 and worthy member of the Royal Physical Society, Dr 

 M'Kay, R.N. It was given to Dr M'Kay by a lime-burner, 

 who followed his vocation at the limestone cliffs which ex- 

 tend along the entrance of the Bay of Melbourne, in the colony 

 of Victoria. The fossil remains of marsupial animals dis- 

 covered in Australia have been chiefly obtained from the lime- 

 stone caverns of Wellington Valley. Major, now Sir Thomas 

 L. Mitchell, formed a considerable collection of these remains ; 

 and they are described by Professor Owen in the second vo- 

 lume of a work entitled ' Three Expeditions into the Interior of 

 Eastern Australia, by Major T. L. Mitchell, Survey or- General. 

 From the examination of these and other fossil mammalian 

 remains, it would appear that they belong, for the most part, 

 to genera still presenting living species in that country. Se- 

 veral, however, from their peculiarities of structure, form the 

 types of new genera. One of these genera is Phascolomys, to 

 which this skull belongs. So far as I have been able to as- 

 certain, we have no skulls, recent or fossil, belonging to this 

 genus in any of the public collections in Edinburgh. This has 

 induced me to exhibit the present specimen to the Royal Phy- 

 sical Society, although the absence of crania from the public 

 museums has precluded me from being able to determine whe- 

 ther this skull belonged to a recent or an extinct species. 



The length of the skull, on its upper coronal surface, mea- 

 sured from the anterior tips of the nasal bones to the perpen- 

 dicular crest of the occiput is 6 T 7 oth inches. From the anterior 

 margin of the frontal bone to the occipital crest, 3 T 9 oth inches. 

 Length of nasal bones, 2 T 7 oth inches. 



