181 



tion, situation, and mode of termination on the outer surface of the 

 integument. 



" The terminal ducts, which are fewer in number than in Ornitho- 

 rhynchus, are similarly grouped together, so as to form a small oval 

 areola, 3 lines in the greater and 2 in the lesser diameter. Each are- 

 ola is situated half an inch from the mesial line, and 3| inches from 

 the orifice of the vestibule of the cloaca. They are much more rea- 

 dily discovered than in Ornithorhynchus, in consequence of the hairs in 

 the Echidna being scantier and stiffer, so that the orifices for their 

 transmission are larger than the orifices of the ducts, which is the 

 reverse of what is observed in Ornithorhynchus : this, however, may 

 not be the case in the fully developed gland. The areola are also 

 slightly raised above the surrounding integument, but there is no 

 vascular rete or erectile tissue discoverable at these parts. The lac- 

 tiferous ducts, before penetrating the corium, pass between the fibres 

 of a dense panniculus carnosus, which is here, as in Ornithorhynchus, 

 interposed between the glands and the integument. The number of 

 the ducts is about sixty. The lobules of the gland are proportion- 

 ally shorter and broader. Their texture under the lens appears the 

 same as in Ornithorhynchus ,• that is to say, minutely cellular, and 

 in neither instance consisting of simple cceca or elongated follicles. 

 From their small size in the Echidna they could not be injected. 



" The smallest size which these glands have presented in Or- 

 nithorhynchus is about one third larger than those in the Echidna now 

 exhibited ; in this state the ovary and uterine tubes were small, and 

 apparently in a state of quiescence. When the ovary is fully deve- 

 loped, and the uterine tubes correspondent^' enlarged, the mammary 

 glands are about 2 inches in the long, and 1 in the short, diameter. 

 When the ovary is found large but flaccid, and apparently after hav- 

 ing shed its contents ; and when the uterine tubes are still large j 

 then the mammary glands exhibit their greatest development, equalling 

 5 inches in the long, and 3 in the short diameter, and being nearly 

 half an inch in thickness. In this state they may be readily injected ; 

 when the lactiferous ducts, to the number of about one hundred and 

 fifty, are seen to terminate in a small oval areola on the external 

 surface, not on any raised eminence, but on the level integument, 

 from which the hairs grow as freely as in the surrounding parts. 

 Nevertheless, from the glands being confined to the female, and ex- 

 hibiting by their variation of size that their function is temporary, 

 and as the period of their greatest activity is shown by the state of 

 the uterine organs to be subsequent to the development and expul- 

 sion of the fcetus,they must be regarded as being true mammary glands, 

 destined to provide nourishment for the newly-born animal. The 

 peculiar development of the panniculus carnosus over the ventral re- 

 gion, both in Echidna and Ornithorhynchus, will assist in explaining 

 the mode in which the lacteal secretion is coveyed from the parent 

 to the offspring. The gland lying between this muscle and the ex- 

 panded cartilages of the ribs and the marsupial bones, is subject to 

 compression, and the young animal need only apply its soft and flexi- 

 ble lips to the areola in order to receive the secretion." 



