Dec. 



1884] 



NA TURE 



L'n des oeufs ^tait cassd, et j'en ai examine la surface in- 

 terne, laquelle m'a paru etre aussi formee par un depot 

 de trts-petits grains de la matiere calcaire." He further 

 states that the dimensions and form of these eggs remind 

 him of those of many of the Saurian reptiles and Ophi- 

 dians ; whilst Jarrel, who examined them, came to the 

 conclusion that they differed as much from the eggs of 

 birds as from those of reptiles. 



Fig. I is copied from a drawing which accompanies the 

 paper of Geoffrey St. Hilaire, and represents its actual 

 size and form. 



Of the nine eggs which were discovered in the nest 

 four were brought to England, and of these two found 

 their way to the Manchester Museum, where, Prof. 

 Williamson has kindly informed me — whilst he was 

 curator, from 1835 to 1838 — he distinctly remembers 



their being placed and labelled as " eggs of Duck-billed 

 Platypi 



In 1826 Meckel, of Halle, had published a monograph 

 on Ornithorhynchus paradoxus (Leipzig, 1826), wherein he 

 announced the discovery of mammary glands, rudimentary 

 in condition, but still undoubtedly present, and serving 

 for the nutrition of the young ; Geoffrey St. Hilaire, who, 

 as before said, was strongly of opinion that the Monotremes 

 could not be included amongst the Mammalia, suggested 

 that the nature of these glands had not been sufficiently 

 studied, and that instead of being mammary they were 

 very probably analogous to those spread out on the flanks 

 of aquatic reptiles, and which served to lubricate the skin ; 

 if this were not the case, he further suggested a com- 

 parison between them and certain odoriferous glands 

 existing in the neighbourhood of the mammary glands in 

 shrews.' 



To these criticisms Meckel urged in reply the strong 

 argument that they were only known to exist in female 

 Monotremes, the males possessing no such structure, and 

 later still Owen published his account of the "Mammary 

 Glands of Ornithorhynchiis paradoxus " {Phil. Trans. 

 1832). In this paper also he quotes the following passage 

 from Meckel (" Ornithorhynchi paradox.' Anatome," 

 p. 58) : — " The difference between the bringing forth of 

 living young and of eggs is really very small, and by no 

 means of an essential nature : birds have accidentally 

 hatched the eggs within the abdomen, and so produced a 

 living foetus — an occurrence which has been induced by 



1 Proc. Zool. Soc, 1S33, pp. 28 and 91 ; also, "Memoir on the Abdominal 

 Glands of Ornithorhynchus, falsely presumed to be mammary, but which 

 secrete, not milk, but mucus, destined for the first nutriment of the young 

 when newly hatched," Gazette Mtdicale, February 18, 1833: also, Annates 

 des Sciences Katurelles, torn. !x. p. 457. 



direct experiment ; and lastly the generation of the 

 Marsupial animals is very similar to the oviparous mode." 

 Meckel, Owen says, deems it " very probable that as 

 the Ornithorhynchus approaches still nearer than the 

 Marsupials to birds and reptiles, its mode of generation 

 may be in a proportionate degree analogous." 



Somewhat later Owen published an account of an 

 Ornithorhynchus fcetus, 1 which measured only two inches 

 in length. After describing its external appearance he 

 says, " On the middle line of the upper mandible, and a 

 little anterior to the nostrils, there is a minute fleshy 

 eminence lodged in a slight depression. In the smaller 

 specimen this is surrounded by a discontinuous margin of 

 the epidermis, with which substance therefore, and pro- 

 bably (from the circumstance of its being shed) thickened 

 or horny, the caruncle had been covered. It is a structure 

 of which the upper mandible of the adult presents no 

 trace, and is obviously analogous to the horny knob which 

 is observed on the upper mandible in the fcetus of some 

 birds. I do not, however, conceive that this structure is 

 necessarily indicative of the mandible's having been 

 applied, under the same circumstances, to overcome a 

 resistance of precisely the same kind as that for which it 

 is designed in the young birds which possess it. The 

 shell-breaking knob is found in only a part of the class, 

 and although the similar caruncle in the Ornithorhynchus 

 affords a curious additional affinity to the Aves, yet as all 



the known history of the ovum points strongly to its ovo- 

 viviparous development (see also Phil. Trans., 1834, 

 P- 555); the balance of evidence is still in favour of this 

 theory." 



Later still {Phil. Trans., 1865, p. 671) he published a 

 paper on the " Marsupial pouches, mammary glands, and 

 mammary fcetus of the Echidna hystrix," wherein he 

 proved that the same caruncle was present in the Echidna 

 foetus, and further that this was carried about by the 

 mother in a pouch (two being present in each individual, 

 one on either side the middle ventral line), into which 

 opened the mammary glands. 



Owen adheres firmly to the opinion that the Monotremes 

 are ovo-viviparous, in which opinion he is supported by 

 the evidence of, amongst others, Sir E. Home {Phil. 

 Trans., 1802, p. 67), whose account is probably the 

 earliest notice of any detail, which was published in 

 England with regard to the internal anatomy of Ornitho- 

 rhynchus. 2 Home says at the close of his paper, " this 

 animal having no nipples and no regularly formed uterus, 

 led me to examine the female organs in birds to see if 

 there was any analog)' between the oviducts in any of 

 that class and the two membranous uteri of this animal : 



1 Trans Zool. Soc, vol. i. p. 222 ; also Proc. Zool. Soc, 1S34, p. 43- 



2 For one of the earliest figures, see Shaw's Naturalists Miscellany, 

 vol. 1.x. 1799, and for figure of Echidna vide op. cit. vol. iii. 1792, under name 

 of Myrmecophaga aculeata. Shaw says of Echidna, " It is also a most 

 striking instance of that beaut' ful gradation so frequently seen in Nature, by 

 which creatures of one tribe or genus approach to those of a very different 

 one. It forms a connecting link between the very distant genera of Hystrix 

 and Myrmecophaga : having the external aspect of the one with the mouth 

 and peculiar generic characters of the other." 



