I lO 



FOSSIL ECHIDNAS 



many other mammals." In Echidna, too, but not in Ornitho- 

 rhynchus, the hemispheres are well convoluted, though the arrange- 

 ment of these convolutions cannot be brought into line with what is 

 known concerning the convolutions upon the hemispheres of other 

 mammals. It had been stated that in these animals, at least in 

 Echidna, there were only two optic lobes, as in lower vertebrates, 

 instead of the mammalian four. The late Sir AV. H. Flower set 

 this matter at rest,^ and showed that Echidmi was in this respect 

 typically mammalian. The absence of the corpus callosum is 



one of the principal features separ- 

 atino- the Monotremes from other 

 mammals. 



The Monotremata are repre- 

 sented to-day by two types, Ornitho- 

 rhyncluis and Echidna, which are 

 no doubt worthy of l)eing placed in 

 separate families. Fossil remains 

 of the group (apart from the prob- 

 lematical Multituberculata) are only 

 known from rieistoceue times in 

 Australia, and consist of the bones 

 of a large species of Echidna, and 

 some fragments of Ornithorhynclius, 

 indicating a smaller animal than 

 the living Platypus. 



Fam. 1. Echidnidae. — This 

 family contains two genera, of which Echidna is the older and 

 much the better known. The skin is abundantly covered with 

 spines, with which are mingled hairs. The snout is tapering, 

 the tail rudimentary, and the fingers and toes five in number. 

 The spur and glaud upon the calcaneum are smaller than iu 

 Ornithorhynchits. The claws are very strong, serving to tear 

 open the ants' nests, upon the inhabitants of which the Echidna 

 feeds, licking them up with a long extensile tongue like that of 

 Myriaeco'iiluiga. In relation to this habit the salivary glands are 

 enormously developed, and indeed the animal has been con- 

 founded with Myrmecophaga," as the vernacular name " Australian 

 Anteater " exemplifies. 



1 Proc. Zool. Soc. 1861, p. 18. 

 ^ Myrviecoiiliaga. acuhata was the name given hy Shaw. 



Fig. 5.3. — Brain of Ei-hidiia aciileata, 

 dorsal view. (Nat. size.) (From 

 Parlver and Haswell's Zoology. ) 



