Royal Society. 419 



PROCEEDINGS OF LEARNED SOCIETIES. 



ROYAL SOCIETY. 



March 2, 1865. — Major-General Sabine, President, in the Chair. 



" On the Marsupial Pouches, Mammary Glands, and Mammary 

 Foetus of the Echidna hystrix." By Professor Owen, F.R.S. 



In a communication to the Royal Society oil the generative economy 

 of the Monotremata*, Prof. Owen showed that the ovum left the 

 ovarium with a spherical vitellus \\ line in diameter, and attained 

 a diameter of 3^ lines in the uterus, the increase of size being due to 

 increase of fluid between the chorion and vitelline tunics. This fluid, 

 homologous with the albumen of the egg of oviparous vertebrates, did 

 not coagulate in alcohol, and the only change presented by the vitellus 

 of the largest observed ovum was a separation from the "food-yolk" 

 of a " germ-yolk " in the form of a stratum of very minute granules, 

 adhering to part of the membrana vitelli. There was no trace of 

 decidua in such impregnated uteri ; the smooth chorion was firmer 

 than that of uterine ova of Rodentia ; whence, and for other reasons 

 given in the Paper above cited, it was inferred " that the Monotremata 

 were essentially ovo-viviparous." 



. The impregnated uteri of the Ornithorhynchus there described 

 were of females killed in the month of October. In the early part 

 of December 1833, young Ornithorhynchi, obtained from the nest, 

 were transmitted by Dr. George Bennett, F.L.S., of Sydney, N.S.W., 

 to Prof. Owen : they were naked, blind, with short, broad, flexible, 

 and softly labiate mandibles, the tongue proportionally large, and 

 reaching to near the end of the mandibles ; the mouth not round, 

 as in the mammary foetus of Marsupials, but a wide trausverse 

 slit ; a pair of small patulous nostrils opened upon the upper man- 

 dible, and between them was a small prominence resembling the 

 knob on the beak of the newly-hatched chick, but softer, and 

 lacking the cuticle, which had been torn off. There was no trace 

 of navel or umbilical cicatrix. 



The phases of the development of the mammary glands of the 

 Ornithorhynchus were the subject of another communication, and, 

 with the peculiar formation of the mouth of the young animal, 

 demonstrated that it was nourished by milk as other mammals. 

 The smallest of the young of the Ornithorhynchus so obtained did 

 not exceed two inches in length. 



At the early part of the present year (1805), Prof. Owen received 

 from Dr. Mueller, F.R.S., of the Botanical Gardens, Melbourne, 

 Australia, a female Echidna {Ornithorhynchus Hystrix, Home, 

 Echidna Hystrix, Cuv.), with a young one, which the captor found 

 adhering to the mother, as he supposed, by a nipple. They were 

 transmitted in spirits, and their description forms the chief subject 

 of the present communication. In regard to the parent, the de- 

 scription is limited to the parts concerned in generation. 



* " On the Ova of the Ornithorhynchus paradoxus" Philosophical Trans- 

 actions, vol. cxxiv. p. 555. 



