MONOTREMATA 



something like that of a duck, bordered by a naked and very sensitive 

 membranous expansion. The place of teeth in the adult is supplied 

 functionally by horny structures, elongated, narrow, and sharp- 

 edged, along the anterior part of the sides of the mouth, and broad, 

 flat-topped or molariform behind. Functional molar teeth present 

 in the young and adolescent condition. Legs short, fitted for 

 swimming ; feet webbed, each with five well-developed toes armed 

 with large claws, beyond which in the fore feet the interdigital 

 membrane is extended. Vertebrae: C 7, D 17, L 2, S 2, Ca 21. 

 Acetabulum not perforated. Tongue not extensile. Mucous mem- 

 brane of small intestine covered with delicate, close-set transverse 

 folds or ridges. Tail rather short, broad, and depressed. Eyes 

 very small. Fur close and soft. 



The Duck-billed Platypus (Platypus anatinus) was the name 

 assigned to one of the most remarkable of known animals by 

 Shaw, who had the good fortune to introduce it to the notice 

 of the scientific world in the Naturalist's Miscellany (vol. x., 1799). 

 In the following year it was independently described by Blumenbach 

 (Voigts Magazin, ii. p. 205) under the name of Ornithorhynchus 

 paradoxus. Shaw's generic name, although having priority to that 

 of Blumenbach, could not be retained, as it had been used at 

 a still earlier time (1793) by Herbst for a genus of Coleoptera. 

 Ornithorhynchus is therefore now universally adopted as the scien- 

 tific designation, although Duck-billed Platypus or Duck-bill may 

 be conveniently retained as a vernacular appellation. By the 

 colonists it is called " Water-Mole," but it need scarcely be said, 

 its affinities with the true moles are of the slightest and most 

 superficial description. Until the last few years the early stages 

 of the development of the young were not fully known. It had, 

 indeed, been repeatedly affirmed, in some cases by persons who 

 have had actual opportunities of observation, that the Platypus lays 

 eggs ; but these statements were generally received with scepticism 

 and even denial. This much-vexed question was, however, settled 

 by the researches of Mr. W. H. Caldwell in 1884, who found that 

 these animals, although undoubtedly mammals throughout the 

 greater part of their structure, are oviparous, laying eggs, which in 

 the manner of their development bear a close resemblance to the 

 development of those of ' the Reptilia. Two eggs are produced at 

 a time, each measuring about three-fourths of an inch in its long, 

 and half an inch in its short, axis, and enclosed in a strong, flexible, 

 white shell. 



The Platypus is pretty generally distributed in situations 

 suitable to its aquatic habits throughout the island of Tasmania 

 and the southern and eastern portions of Australia. Slight variations 

 in the colouring and size of different individuals have given rise to 

 the idea that more than one species may exist ; but all naturalists 



