286 CRITIQUES AND ADDRESSES. [xi. 



mode of origin of the Monodelphia from these is a very 

 difficult problem, for the most part left open by Professor 

 Haeckel. He considers the PrtosimicB, or Lemurs, to be 

 the common stock of the Deciduata, and the Cetacea 

 (with which he includes the Sirenia) to be modified 

 Ungulata. As regards the latter question, I have little 

 doubt that the Sirenia connect the Ungulata with the 

 Proboscidea ; and none, that the Cetacea are extremely 

 modified Carnivora. The passage between the Seals 

 and the Cetacea by Zeuglodon is complete. I also think 

 that there is much to be said for the opinion, that the 

 Insectivora represent the common stock of the Primates 

 (which passed into them by the Prosimice), the Chei- 

 roptera, the Rodentia, and the Carnivora. And I am 

 greatly disposed to look for the common root of all 

 the Ungulata, as well, in some ancient non-deciduate 

 Mammals which were more like Insectivora than any- 

 thing else. On the other hand, the Edentata appear to 

 form a series by themselves. 



The latter part of this notice of the Natilrliche 

 Scliopfungs-Geschichte, brings so strongly into pro- 

 minence the points of difference between its able 

 author and myself, that I do not like to conclude 

 without reminding the reader of my entire concurrence 

 with the general tenor and spirit of the work, and of 

 my high estimate of its value. 



