I OBSERVE in NATURE (vol. xvi. p. 439) that a doubt arises respecting the Echidna or Australian porcupine (recently renamed Tachyglossus) and the Ornithorhynchus being found in Northern Australia. It does exist in Queensland, but how far north it is impossible to decide until we are better acquainted with that extensive territory. The fact of one having been found by Mr. Kennedy, as mentioned by Mr. Forbes at Plain Creek in lat. 21° S. is, as far as the published statement can be depended upon, correct, and was never considered by any Australian in Queensland as a matter of doubt, as they were well acquainted with the animal; but whether the Tachyglossus was the same or of a different species I do not consider has been sufficiently noticed; whether it was the Tachyglossus hystrix, or with sufficient distinctive characters, as has been recently found in that ot New Guinea to make it a new species, is not known, as ordinary travellers are not able to distinguish those characteristic differences which would immediately strike the experienced naturalist. The species found in the vicinity of Darling Downs, &c., is evidently the Tachyglossus hystrix, and from a recent letter received from my son, Mr. G. F. Bennett, he finds no difficulty in procuring specimens of this species near Foowoomba by offering rewards for those procured at certain intervals of time, to enable him to carry out his investigations on the mode of generation of the Monotremata, and if possible to procure the impregnated uterus of that animal, as well as that of the Ornithorhynchus, as in both animals it no doubt will be identical. As far as regards the rudimental pouch in the Echidna it is only able to be found in that animal during the breeding season, and I could never detect it at any other time. It is mentioned by Prof. Owen in his memoir on the young of the Echidna (Philosophical Transactions, 1865, p. 678), and indeed it has been a well-known fact for some period of time, as some years ago I doubted the assertion and public attention was most particularly drawn to it, and the fact was ascertained beyond doubt even before the publication of Prof. Owen's paper. The Ornithorhynchus being an aquatic animal does not possess a pouch at any time. With respect to the New Guinea species of Echidna the question whether the Tachyglossus lawsei and T. bruijmi are distinct species can now be decided, as I observe that examples of both sexes of T. bruijnii have been obtained in the mountains on the north coast of New Guinea at an elevation of about 3,500 feet. That a new and somewhat analogous species of Tachyglossus may yet be discovered in Northern Australia I consider very probable.