Miscellanea. 181 



tjiis plaintifs qui oiFrait quelques rapports avec ceux d'un petit 

 coc^hon, et qui allaient toujours augmentant: raccoiiplement durait 

 cinq ou six minutes, ensuite les deux animaux jouaient ensemble 

 pendant plus d'uue lieure." Ih. p. 130. 



We have seen tliat M. Verraux draws his conclusions from the 

 ovavia of the female, that she is ovo-viviparous. The period of 

 gestation has yet to be determined. I have calculated it at about 

 six weeks, judging from the size of the uterine ova in a female 

 killed December 8th in the Murrurabidgee river, and from that 

 of young ones found in the nest in the banks of the same river 

 two months afterwards. M. Verraux, alluding to the habit of 

 the female to quit her burrow during the heat of the day, says 

 that this occurs — " lorsqu'elles out des petits, c'est-a-dire depuis 

 iiovembre jusqu'en Janvier," ib. p. 132: meaning, that she has 

 young ones in her nest at that time. He states that " a gentleman 

 in Tasmania, Dr. Casey, had discovered (but the date is not given) 

 two nests of the Orniihorhynchus, one with a single young one, the 

 other with two ; they were naked, but vigorous in proportion to 

 their size. Their beak did not at all recall the form of that of the 

 adult, but was short, broad and thick, and could embrace in that 

 state the mammary areola concealed by the hairs of the mother." 

 This accords with the description and iigures of the beak of the 

 j^ouug Ornithorhynchus given in my memoir on the young Ornitlio- 

 rhynchus in the 1st vol. of the Zoological Transactions ; where it is 

 also shown, that " the tongue, which in the adult is lodged far back 

 in the mouth, advances in the young animal close to the end of the 

 lower mandible; all the increase of the jaws beyond the tip of the 

 tongue, which in the adult gives rise to a form of the mouth so 

 ill-calculated for suction or application to a flattened surface, 

 is peculiar to that period, and consequently forms no argument 

 against the fitness of the animal to receive the mammary secretion at 

 an earlier stage of existence. The disproportionate breadth of the 

 tongue is plainly indicative of the importance of the organ to the 

 young animal both in receiving and swallowing its food. The man- 

 dibles are surrounded at their base by a thin fold of integument, 

 which extends the angle of the mouth from the base of the lower jaw 

 to equal the breadth of the base of the upper one, and must increase 

 the facility for receiving the milk ejected from the mammary areola 

 of the mother." The airangement of the muscles for compressing 

 the mammary glands I had described in a previous memoir. (Phil. 

 Trans. 1832, p. 517). 



M. Verraux adds : — " The young ones, while suckling, continually 

 rub or triturate the mother's belly with their fore-feet, and sometimes 

 with their hind-feet." " At the end of fifteen to twenty days the new- 

 born are covered with a silky hair, and are able to swim." (Eevue Zool. 

 p. 132). 



And he likewise describes another mode in which the young obtain 

 their lacteal nourishment:—"! redoubled my attention and care, 

 and by dint of perseverance, having at my disposition (always on the 

 banks of the New Norfolk)* a pretty considerable number of adults and 

 young, I saw the latter accompany their mothers, with which they 

 played, especially when they were too far from the bank to take their 



* River Derwent. 



