Gi6 MR. E. R. ALSTON ON ACANTHOMYS LEUCOPUS. [June 1 7, 



Although Dr. Jentink places the species in the genus Mus, he re- 

 tains Gray's specific name on the ground that Mus leucopus (Raf.) 

 has since been separated as a Hesperomys. In this I cannot 

 agree ; because a species has been removed to a new genus its name 

 does not become unoccupied in the old one. Surely Dr. Jentink 

 would not think it admissible to name a new Mouse Mus aquaticus 

 because the Linnsean Mus aquaticus has been separated as an Ar- 

 vicola 1 Nor can I see any analogy in his further suggestion that 

 "if Alston objects to the name of this species he should also reject 

 the name Uromys rufescens, and adopt the specific name muscivora, 

 Pierson Ramsay, because, under the name of Mus rufescens, a Mouse 

 was already described by Gray." The cases will only be parallel 

 when Dr. Jentink can prove that my Uromys rufescens ' is a true 

 Mus. and does not belong to the perfectly distinct genus Uromys. 

 When he has shown this I will readily withdraw my name in favour 

 of Mr. Ramsay's. 



The following is a fuller description than Gray's of the North- 

 Australian Spiny Rat, which I propose to call 



MUS TERR.E-REGIN.E, Sp. n. 



Acanthomys leucopus, Gray, P. Z. S. 1867, p. 598 (descr. orig., 

 vide supra). 



Mus leucopus, Jentink, Notes fr. Leyden Mus. i. p. 8 (part., nee 

 Desmarest). 



Fur stiff and harsh both above and below, most of the hairs being 

 developed into flattened channelled spines ; on the back are many 

 longer cylindrical hairs. Whiskers weak, not longer than the 

 head, mixed black and white. Ears rather large, rounded, perfectly 

 naked. Feet remarkably large and stout. Tail considerably shorter 

 than the head and body, naked, the scattered minute hairs being 

 hardly visible to the naked eye. Colour above dark reddish brown 2 , 

 the spiny hairs being dusky, tipped with rufous, the longer hairs 

 black ; lips, lower parts of cheeks, chin, breast, belly, inside of 

 limbs, and feet yellowish white 3 ; tail dusky, irregularly marked 

 with yellowish patches and rings. 



Measurements of type specimens (a, an adult, and b, a young 

 female) : — 



a. 



in. miUims. 



Length of head and body .... 8 25 = 210 



tail 7-10 = 180 



„ ear *75 = 20 



hind foot 1-57 = 40 



1 P. Z. S. 1877, p. 124, pi. xviii. 



2 Not greyish brown as stated by Gray. 



5 The yellowish tinge may be due to the spirit in which the specimens are 

 preserved. 



