Prof. Owen on the Ornithorhynchus. 319 



mouvoir, car POrnithorhynque est d^un naturel excessivement 

 mefiant, je pus suivre tous leurs mouvements. Le male, apres 

 avoir poursiiivi sa femelle plus d^une heure, finissait toujours par 

 Famener au milieu des roseaux. La, se cramponant solidement 

 k Faide de son bee, il tenait fortement la peau du cou, tandis 

 que les eperons s'appliquaient sur la partie posterieure. La 

 femelle, tout en se debattant energiquement, nageait et poussait 

 des oris plaintifs qui offrait quelques rapports avec ceux d^un 

 petit coclion, et qui allaient toujours augmentant : Paccouplement 

 durait cinq ou six minutes, ensuite les deux animaux jouaient 

 ensemble pendant plus d^une heure/' lb. p. 130. 



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

 ovaria 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 Murrumbidgee 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 ont des petits, c^est-k-dire depuis 

 novembre 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. Casy, had discovered (but the date is not given) 

 two nests of the Ornithorhynchus, 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 figures of the beak of the 

 young Ornithorhynchus given in my memoir on the young Orni- 

 thorhynchus 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 

 sm'face, is peculiar to that period, and consequently forms no ar- 

 gument 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 mandibles 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 arrange- 



