*252 DR R. BROOM ON THE 



Chiroptera, and Ungulata ; in the latter, the Edentata, and probably the Rodentia. 

 There should be no difficulty in placing the Sirenia in its proper group, as in it there is 

 known to be a well-developed organ of Jacobson. The position of the Cetacea will have 

 to be decided by other characters. 



In the Marsupialia or Metatheria there is no doubt we have a most satisfactory 

 sub-class, but there seems reason from the present investigation to divide it into two 

 sub-orders, the Polyprotodontia and the Diprotodontia. The position of the Bandicoots 

 has frequently been a matter of doubt, and there are unquestionably some Eutherian 

 characters to be met with in the group, as the presence of an allantoic placenta, as dis- 

 covered by J. P. Hill, the ossified patella, and a character which I have observed in no 

 other marsupial, the intercommunication of the two nasal cavities behind the region of 

 Jacobson's organ. Notwithstanding these advanced characters, there is little doubt but 

 that the Peramelidse are rightly placed with the other Polyprotodonts, as has been done 

 by Thomas. 



The Rodents, as has already been shown, have the organ so specialised that it is a 

 little difficult to decide whether we have an advancement of the early condition, or a 

 specialisation of the later ; the evidence, however, mostly points to the former conclusion, 

 and at present we may tentatively regard the Rodentia as belonging to the Archaso- 

 rhinata. This being so, we may classify the Mammalia thus : — 

 Class — Mammalia. 



Sub-class I. Protheria. Order Monotremata. 



Sub-class II. Metatheria. Order Marsupialia. S. 0. Polyprodontia. 



S. 0. Diprotodontia. 

 Sub-class III. Eutheria. Group 1. Archseorhinata. Order Edentata. 



Order Rodentia (?). 

 Group 2. Csenorhinata. Order Chiroptera. 



Order Insectivora. 

 Order Carnivora. 

 Order Primates. 

 Order Ungulata. 

 Order Sirenia. 

 Order Cetacea. 

 A further subdivision of the orders in the group Csenorhinata might be made, the 

 Chiroptera, Insectivora, Carnivora and Primates being apparently more nearly allied to 

 each other than to the Ungulata. 



In conclusion, I must express my thanks to the following gentlemen for their kind- 

 ness in assisting me with specimens and in other ways : — Sir William Turner, 

 Sir William Flower, Mr F. E. Beddard, Dr Elliot Smith, Mr A. G. Hamilton, 

 Professor Wilson, Professor D'Arcy Thompson, and Dr Beard. 



