HYPSIPRYMNUS MUBINUS. 179 



a skull, now before me, agreeing in size with the 

 dimensions given below, is also from a female animal. 



The dimensions of the skull of the Poto-Roo are 

 as follows : 



Total length, 3 inches 1^ lines; width, 1 inch 7 

 lines; from front of anterior incisor to first molar, 10 

 lines ; from do. to hinder part of last molar, 1 inch 

 8^ lines ; width between orbits, 8 lines. 



In Van Diernen's Land is a species of Kangaroo- 

 Rat, which appears to me to be identical with the 

 animal above described, and if it be, the following 

 dimensions, furnished by the skull of one of these 

 animals, would indicate the specimen to have been 

 a male that is, presuming the conjecture of the 

 sexual difference of size to be correct. 



Length, 3 inches 3 lines; width, 1 inch 9| lines; 

 from front of anterior incisor to first molar, 1 1 

 lines ; longitudinal extent of molars on each side 

 of the upper jaw, 10^ lines. 



Shaw was acquainted with only two species of 

 Macropodidce, the great Kangaroo, (Macropus gigan- 

 teus) and the present species of Kangaroo-Rat, the 

 name Macropus minor given to this small animal, 

 since the discovery of numerous Kangaroo-Rats, 

 (some of which are smaller than the Poto-Roo,) 

 has become peculiarly inappropriate, I have thought 

 it desirable, therefore, to choose the next oldest name 

 I can find applied to it. 



