GENESIS OF MAN. 53 



and was thus the progenitor of all that now possess it, and hence 

 of man himself. This creature, which forms the fifteenth stage of 

 man's genealogy, Haeckel calls the Protamnion. Out of it was 

 developed primarily the great reptilian class, from which proceeded 

 later the birds, with neither of which has man any direct connec- 

 tion. The origin of the mammals, however, must also be sought 

 in the Protamnion stock, from which this class, too, must have pro- 

 ceeded, — perhaps simultaneously with the reptilian branch, though 

 in quite a different direction. The skull of all reptiles and birds 

 is articulated to the atlas by means of a single condyle, while in 

 mammals this condyle is double. From this circumstance the 

 reptiles and birds have been designated by the common term 

 Monocondylia. In them, also, the lower jaw is. composed of several 

 pieces, and movably joined with the skull by a special process, 

 while in the mammals it consists only of a pair of pieces, and is 

 immediately connected with the temporal bone. The further dis- 

 tinction between the scales and feathers of the former and the 

 hairs of the latter, is likewise an important one. The complete 

 diaphragm of mammals, dividing the thoracic entirely from the 

 abdominal viscera, and which is only partial in the Monocondylia, 

 is a further very characteristic distinction. Finally, the existence 

 of mammary glands in the latter, from which the class takes its 

 name, and which are wanting in all other creatures, not only indi- 

 cates a very distinct position for the mammals, but combines with 

 other characters to place them at the head of the animal series. 



A very distinct race, which Haeckel styles the Promammalia, 

 forming the next or sixteenth stage of man's descent, must have 

 developed out of the Protamnia, and transmitted all these marked 

 peculiarities to the entire mammalian class. Man himself possesses 

 all these special mammalian characteristics, and is therefore a 

 genuine mammal. 



The nearest known living representative of these hypothetical 

 Promammalia are the curious and remarkable Monotremata of 

 Australia and Tasmania. Of the entire sub-class only three forms 

 are known, the singular Orinthorhynchus paradoxus and the 

 Echidna, of which there are two species, E. hystrix and E. sctosa. 

 These animals seem, at first sight, to form an immediate connecting 

 link between the birds and the mammals, as they possess the beak 

 of the former with the lacteal glands of the latter. They further 



