32 MAMMARY APPARATUS OP THE MAMMALIA 



are the first mammary formations which 

 appear in the course of ontogeny in Echidna. 

 These gland areas, it is true, arise very early in 

 the indifferent form of the primary-primordia. 

 The development of the incuhatorium falls in 

 point of time between the first formation of 

 the primary-primordia and their final evolution 



Fig. 14. — Echidna: Semon's Embryo, Stage 53. 



with the appearance of the mammary glands. 

 In contradistinction, then, to the views held by 

 Klaatsch and Ruge, the organs of the mammary 

 apparatus in the case of Echidna are formed 

 in the following order : ( ] ) primary-primordia 

 — that is to say, gland areas ; (2) incuha- 

 torium ; (3) mammary glands. 



