_ tical membrane it is probable that this does not 
_ become organized into a placenta, and that the 
_ Monotremata like the Marsupiata are essentially 
‘ovoviviparous. Since, however, the female Or- 
nithorhynchus has no tegumentary pouch to pro- 
tect a prematurely born offspring, it must be pre- 
sumed that the foetus acquires greater propor- 
tional bulk* and more mature strength by a 
longer continuance within the uterus. In this 
€ase it may be doubted whether the vitelline 
vesicle will suffice for nourishment and respi- 
‘ation through the whole period of develop- 
‘ment, and the allantois and umbilical vessels 
will probably be more expanded for that pur- 
t . 
_ pose 
__ The means of prosecuting this inquiry are 
‘the more likely to be afforded, since, through 
exertions of Mr. Bennett, the period when 
pregnant female may be procured is now 
ertained. Had not a specimen, supposed 
be in this condition, which my friend had 
ained alive, unfortunately escaped from its 
finement, he would, there is little doubt, 
ascertained the true nature of the gene- 
ye product, and the probable duration of 
ation. 
With reference to the latter point, Mr. Ben- 
‘nett observes, that two months after the cap- 
ture of the female specimen with the smallest 
viz. on the 8th of December, 1832, he 
eceeded in laying open one of the burrows 
he Ornithorhynchi on the banks of the Mur- 
bidgee River, in which three living young 
ss were found: they were naked, and mea- 
ed only one inch and seven-eighths in 
h, and he considers them to have been 
tly brought forth. Not having any means 
reserving these specimens, and being at a 
distance from Sydney, they were lost. 
nest was most carefully scrutinized by 
Bennett, but not the slightest trace of an 
hell could be perceived in it. 
he principal points, therefore, in the ge- 
‘ive economy of this paradoxical species 
which still remain to be determined by actual 
observation are— 
_ Ist. The manner of copulation. 
orem The season of copulation. (This is pro- 
_bably at the latter end of the month of Sep- 
_ tember or beginning of October.) 
__ 3d. The period of gestation. (This is pro- 
bab six weeks.) 
_ 4th. The nature and succession of the tem- 
_ porary structures developed for the support of 
_ the foetus during gestation. 
Sth. The exact size, condition, and powers 
_ of the young at the time of birth. 
- 6th. The act of suckling. 
_ @th. The period during which the young 
requires the lacteal nourishment. 
oe The age at which the animal attains its 
fall size. 
I have ascertained the following particulars 
“Wy 
__* In reference to this point it may be observed, 
that the kidneys are not lodged low down in the 
oe in the trae Ovipara, but occupy the posi- 
ion characteristic of the Mammiferous type of 
structure, which allows free space for the enlarge- 
__-‘™ment of the uterus during pregnancy. 
=. 
5] 
MONOTREMATA. 
399 
respecting the young Ornithorhynchus, pro- 
bably not long excluded from the foetal enve- 
lopes, by an examination of two specimens, 
obtained by Lieut. the Hon. Lauderdale Maule, 
from two different nests, discovered by him in 
the banks of the Fish River, Australia, and 
presented by Dr. Weatherhead to the Zoolo- 
gical Society of London. 
Subjoined is an outline of the smaller of 
these specimens of the natural size (fig. 195). 
Fig. 195. 
Young Ornithorhynchus. ( Original. ) 
The following are admeasurements of these 
two specimens :— 
Smaller Larger. 
Ornitho- Ornitho- 
rhynchus. thy eee 
In. Le n L. 
Length from the end of the 
upper jaw over the curve 
of the back to the end of 
the tal «uo eesee eee Oo ee 6 6 
Length from the same points 
in a straight line along the 
abdomiensce a. oo aca ce 2°41 4 0 
Greatest circumference of the 
Od sass cccsew ec dae 
Length of the head 
Length of the upper man- 
GIDIG SE Naveteicice cc asiet tess 
Breadth of the upper man- 
dible at the base 
Thickness of the upper man- 
dible at the anterior margin 0 0 
Length of the lower mandible 0 2 
Breadth of the lower man- 
dible at the base........ 0 
Length of the tail from the 
WBE or occa sieciesieietete ie 
Breadth of the tail at the root 
Length of the fore foot .... 
Breadth of the fore foot.... 
Length of the hind foot.... 
Breadth of the hind foot .. 
Distance between the eyes. . 
Distance between the nostrils 
From the exterior nostrils to 
the end of the mandible 0) 
From the tip of the tongue 
to the end of the lower 
mandible 
wo 
oz: sewowohww p> wo oO 
Nie tom CD Nim in 
o eoocece So S oo Sc o — > 
So 
°o 
