98 Blood of the Ornitliorhynclius. 
of this instrument. The globules were seen distinctly, 
by my friend Mr. Ronald Gunn and myself, to be of a 
discoid character, with a dark central nucleus. They 
were extremely numerous, as compared with those of the 
blood of oviparous animals, and much about the size of 
globules of human blood, with which we examined it 
side by side. 
A careful measurement was made by means of Over- 
hauser’s micrometer; and repeated trials ascertained it 
to be, as nearly as possible, y^^th of an inch. There 
appeared some slight disparity of size in the globules. 
This, however, may probably have arisen from pressure. 
The circular figure of the blood globules in this extra¬ 
ordinary creature is, I think, demonstrative of its 
zoological character, and clearly indicative of the position 
which this genus should be considered to hold. 
The examination of the blood globules of its congener 
the Echidna , will no doubt afford the same results. I u 
the observations made, transmitted light from a lamp was 
used. The density of the blood, together with its very 
florid colour, is further proof of its viviparous character. 
Examinations of the blood of the Macropus elegans 
(wallaby), and of the Petaurus (flying squirrel), have 
enabled me to mention that the blood globules in these 
animals are discoid; those of the kangaroo measuring 
something less than the P art of an inch, and those 
of the Petaurus about T^th. In the latter animal 
one of the globules was nearly TT ^th of an inch i u 
diameter.* 
* Since this paper was written, Dr. Hobson and Mr. E. Bedford 
have examined the blood of a living Echidna ; and the blood globules 
exactly resembled those of the platypus, as described by Dr. H. 
