448 
Miscellanea. 
This was the condition of the rudimental marsupial bones in 
two full-grown females and one male specimen of the Thylacinus : 
in a fourth large and old male a few particles of the bone-salts 
were deposited in the centre of the fibro-cartilage, occasioning a 
gritty feeling when cut across by the knife. 
This unexpected and very remarkable modification of the most 
characteristic part of the skeleton of the Marsupialia, in one of 
the largest of that order, has many important bearings upon the 
physiology of the problematical ‘ ossa marsupialia.’ They have 
been most commonly supposed to serve for the support of the 
marsupial pouch and young; but this pouch is well developed in 
the female Thylacine, and in one of the specimens which I dis¬ 
sected four well-developed teats, each two inches long, indicated 
that it had contained four young ones when, or shortly before, it 
was killed. The existence of the marsupial bones in the male 
as well as the female sex in other marsupial animals had already 
invalidated the above physiological explanation, and it equally 
opposes the idea of the use of the marsupial bones, propounded 
by M. de Blainville,—that they aid in the compression required 
to expel the embryo. Besides, it is not in the females of those 
animals which give birth to the smallest young that we should 
expect to find auxiliary bones for increasing the power of the 
muscles concerned in parturition. My view of the uses of the 
marsupial bones, as explained in the c Philosophical Transactions’ 
for 1834 , is, that they relate more immediately to an increase of 
power in the muscles ( cremastcres ) which wind round them, than 
of those implanted in them : and to the extent to which the car¬ 
tilaginous representatives of the ossa marsupialia in the Thylacine 
strengthen the pillars of the abdominal ring, they must increase 
the contractile force of the compressors of the mammary glands 
and teats, which are situated and surrounded by the cremasteres 
in the Thylacine, as in other Marsupialia. Nevertheless, the almost 
obsolete condition of the ossa marsupialia in the Thylacine, and 
their very various relative sizes in other Marsupialia, are circum¬ 
stances which seem incompatible with the same kind and degree 
of use in all the species : they are very slender, and not above 
half an inch in length in the Myrmecobius , whilst in the Koala 
