AUSTRALIAN jS'ATUKAL HISTORY. 137 



Phascolotherlum, Triconodon, and other forms. Some of our 

 living marsupials resemble tlie Echidna (in the structure of their 

 skull and in their scanty or curiously-arranged teeth), and in this 

 direction the connection between the two lowest orders of mam- 

 mals must be looked for. I regret to say that the most diligent 

 search for Platypus remains has not yet been successful, but of 

 the Echidna I found three fragments of the humerus and a femur, 

 the latter almost perfect, and indicating a larger kind. 



The teeth of the Monotremata consist in the Platypus of four 

 Horny plates without roots or fangs, well adapted for crushing 

 the food. The Echidna is toothless, but at. the posterior end of 

 the mandibular symphysis there is a small alveolus in each ramus, 

 which appears to me indicative of a rudimentary tooth, perhaps 

 corresponding to a canine. The Myrmecobius (with its peculiar 

 skull, which resembles that of the Echidna, but is well provided 

 with fifty-two very small teeth) and the little Tarsipes, with its 

 irregular dentition, appear to be the nearest relations to the 

 Monotremes.* 



{Didelphia or Marsupialia.') 



The teeth of the marsupials — the peculiar arrangement of 

 some, and the presence of almost toothless genera — point, as 

 already stated, to a probable development from the Monotremes. 



When examining the Echidna, with its long spiny tongue, we 

 can easily imagine a kind of connection between this form, the 

 Myrmecobius and the little honey-sucking Tarsipes. Both mar- 

 supials possess a bird-like skull and very weak mandibles, both 

 are covered with comparatively coarse hair, and have few or 

 irregular teeth, not touching each other. One, with a nailless 

 thumb, conjoined inner toes, and only one pair of lower incisors, 

 connects the herbivorous marsupials with the Monotremes ; the 

 other, with many cutting teeth, without conjoined inner toes, 

 with tuberculated grinders and regular canines, appears to diverge 

 towards the marsupial carnivores. With the platypus no such 

 connection can at present be established. We must not forget, 

 however, that all our efforts at elucidation are comparable to 

 looking for a pin in a bale of hay. The dentition of the two 



* It is still an open question how the young of these Monotremeous 

 animals are conveyed to the mammary glands. The Echidna has two deep 

 pouches, about the size of the new-born young, without nipples ; and on two 

 occasions young animals have been found inside, but how they get there we 

 are unable to tell. The general belief that the mother uses her lips in the 

 conveyance is untenable when we consider that the animal is destitute of lips, 

 and has nothing but a stiff beak and paws as clumsy as it is possible to 

 imagine. Year after year passes without a solution of this most important 

 question, and the Echidna will probably have disappeared by the time that a 

 irore liberal-minded generation produces men who will devote a little time 

 and some money to the investigation of his interesting problein. 



