222 MR. R. OWEN ON THE YOUNG OF 
At the time when I was engaged in examining the structure and relations of the 
mammary glands of the Ornithorhynchus in 1832, my friend Mr. George Bennett was 
frequently with me: he became deeply interested in the question, and left England for 
Australia, determined on devoting his utmost endeavours while in that country towards 
its solution. His efforts have been attended with unexampled success, especially when 
it is considered how short a space of time was allowed him for these investigations. The 
results of his observations on the habits and economy of the Ornithorhynchus, he wilt 
himself lay before the Society ; and I shall only here allude to a few of the facts which 
relate more immediately to the subject of the present communication. 
The season of copulation is at the latter end of September or the beginning of the 
month of October. The precise period of gestation, and the condition of the excluded 
product, still remain to be determined ; but in the first week in December Mr. G. Ben- 
nett found in one of the nests of the Ornithorhynchus, three’ small naked embryos, not 
quite two inches in length, and which he therefore supposes, with much probability, to 
have been recently born. These specimens he was unable to preserve, from the want of 
the necessary means in a situation remote from any settlement. 
Fortunately, young specimens of Ornithorhynchus a little further advanced have been 
transmitted through other channels to this country. The Society is indebted for them 
to the prompt liberality of Dr. Hume Weatherhead, and they form the subject of the 
present communication. These specimens are of different sizes: the smaller one rather 
exceeds 2 inches in length, measured from the end of the bill to the end of the tail in 
a straight line ; the larger one is double that size, and is one of those two young ani- 
mals which, with the mother, were taken from a nest on the banks of the Fish River, 
and kept alive for about a fortnight by Lieut. the Hon. Lauderdale Maule?. 
The following are admeasurements of these two specimens. 

Smaller Orni- | Larger Orni- 
thorhynchus. | thorhynchus. 
Length from the end of the upper jaw over the curve of Inches. Lines. | Inches. Lines. 
the back tothe endofthetail . . . ....=.3 9 Geo 
Length from the same points in a straight line along the 
OO st gcse itt ates dete ees oe oe 4 0 
Greatest circumference of the body . . . . . - - 2 9 4 8 
Length of the head 43 84 Lebeaed® 
Length of the upper mandible . : 3 5 
Breadth of the upper mandible at the base . 4 6 
Thickness of the upper mandible at the anterior margin . 4 1 
Length of the lower mandible. . . . . ..-. . 2 24 
1 The left ovary of one of the impregnated wteri exhibited three corpora lutea, and Mr. G. Bennett believes 
that the Ornithorhynchus occasionally brings forth four young ones. 
2 Proceedings of the Committee of Science, Zool. Soc., vol. u. p. 45. 
