181 



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

 integument. 



'■ The terminai ducts, which are fewer in number than in Ornitho- 

 rhynchus, are similarly grouped togetlier, 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 niuch more rea- 

 dily discovered than in Ornithorhynchus, in con.sequence of the hairs in 

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

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

 reverse of what is observed in OrnitJiorhijnihus : this, hovvever, may 

 not be the case in the fuUy developed gland. The areolcB are also 

 slightly raised above the surrounding integument, but thcre is no 

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

 tiferous ducts, before penetrating the coriuvi, pass betvveen the fibres 

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

 interposed betvveen the glands and the integument. The number of 

 the ducts is about si.\ty. The lobules of the gland are proportion- 

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

 šame as in Ornithorhynchus ; that is to say, minutely cellular, and 

 in neither instance consisting of simple caca or elongated foliicles. 

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



" The smallest size which these glands have presented i n Or- 

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

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

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

 loped, and the uterine tubes correspondently enlarged, the mammary 

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

 When the ovarv 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, eąualling 

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

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

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

 lifty, 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 sho\vn by the statė of 

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

 sion of the foetus,lhey mušt 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 \vhich the lacteal secretion is coveyed from the parent 

 to the oft'spring. The gland lying betweeti this musele and the ex- 

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

 conipression, and the young animal need onlyapply its soft and flexi- 

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



