On a neio Genus 0/ Echimyinse. 113 



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

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

 m^ 9. Combined length of five s.nali anterior teeth 4*2; 

 combined length of four molari;oi ni teeth {p*-m^) 4'2 ; lower 

 tooth-row 8'3 (9*8 in iV. typkhps) ; three anterior teeth '2'S ; 

 four mohiriform teetii 4'4. 



Unb. Woilal, N.W. Australia. 



2^ype. Adult female. Skin no. 10442 in West Australian 

 Museum, Perth. iSkull 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 i\luseuiu are 

 deserving of our gratitude for permitting a comparison to be 

 made of tlie unique Wollal specimen with the allied form of 

 Central Australia. 



XII. — A new Oenus of Ecbimyinse. 

 By Oldfield Thomas. 



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



Among some Amazonian mammals sent for determination by 

 the autliorities of the Goeldi IMuseum, Para, there occurs a 

 single specimen of a Spiny-rat collected by I'raulein 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 immber 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 liystricomorpii rodents, but it represents 

 a phase of development not actnally found in the Echimyiiiae, 

 while somewhat similar to tliat of Krethizon 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 Mesomi/s. 

 Ann. ct Ma(/. N. Hint. Ser. 0. Vol. vi. 8 



