On a new Genus of Echimyina?. 113 



zygomatic breadth 14*8 ; breadth across forehead 9'6 ; inter- 

 orbital breadth 8"3 ; palatal length 10'5 ; breadth outside 

 m 1 9. Combined length of five snail anterior teeth 4*2; 

 combined length of four molariroi m teeth Ql> 4 -»* 3 ) 4*2 ; lower 

 tooth-row 8'3 (9'8 in N. typlilops) ; three anterior teeth 2'$ ; 

 four tnolariform teeth 4*4. 



Hab. Wollal, N.W. Australia. 



Type. Adult female. Skin no. 10442 in West Australian 

 Museum, Perth. Skull transferred by exchange to British 

 Museum, B.M. no. 20.5.21.1. Captured 29th August, 

 1910. 



It is a matter of very great interest to find this anomalous 

 type of marsupial represented by a second species in the far 

 North-west, and the authorities of the Perth Museum are 

 deserving of our gratitude for permitting a comparison to be 

 made of the unique Wollal specimen with the allied form of 

 Central Australia. 



XII. — A new Genus of Echimyinae. 

 By Oldfield Thomas. 



(Published by permission of the Trustees of the British Museum.) 



Among some Amazonian mammals sent for determination by 

 the authorities of the Goeldi Museum, Para, there occurs a 

 single specimen of a Spiny-rat collected by Fraulein Dr. E. 

 Snethlage on the River Tapajoz, and this proves to represent 

 a new genus of that most interesting group. It belongs to 

 the series of genera related to Echimys (better known as 

 Loncheres), and, like the greater number of them, is modified 

 for an arboreal life. Its dentition is of the special type, 

 called "reduced heptamerous" by Miller, which crops up so 

 frequently among the hystricomorph rodents, but it represents 

 a phase of development not actually found in the Echimyinse, 

 while somewhat similar to that of Erethizon and others. 



The animal's external appearance is very striking and quite 

 peculiar to itself. 



Lonchothrix, gen. nov. 



Pelage highly spinous. Feet short. Tail tufted. 

 Skull closely similar to that of Mesomys. 

 Ann. & Mag. N. Hist. Ser. 9. Vol. vi. 8 



