644 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. XXXIV. 
MUS “RATTUS.” 
1905. Mus neglectus, SCHNEIDER, Zool. Jahrb. Syst., XXIII, p. 111. 
Four rats from the Siak region are referable to this group. 
They are very little if at all different from Mus neglectus Jentink, 
so far as may be judged by descriptions and measurements. For list 
of localities and measurements see table, page 649. 
MUS EPHIPPIUM Jentink. 
1880. Mus ephippium JENTINK, Notes Leyden Museum, II, p. 15. 
1905. Mus ephippiwm, SCHNEIDER, Zool. Jahrb. Syst., XXIII, p. 111. 
A small rat, an old male, from the Siak River, may be referred to 
Mus ephippium provisionally. It does not agree entirely with the 
original description or measurements, but without an actual com- 
parison of specimens it does not seem advisable to recognize another 
small species of rat from Sumatra. 
For measurements see table, page 649. 
MUS ASPER Miller. 
1900. Mus asper Miuuer, Proc. Biol. Soc. Washington, XIII, April 21, 1900, 
p. 145. (Type-loecality, Trong, Lower Siam.) 
Fifteen small spiny rats collected by Doctor Abbott in eastern 
Sumatra may be referred to Mus asper Miller. They are all small 
brightly colored rats with rusty bellies, and closely resemble the origi- 
nal series of Mus asper from Trong as well as the other bright colored 
rats from the Malay Peninsula referable to the same species. For 
list of localities and measurements see table, page 648. The single 
skin from Aru Bay is considerably darker than the other specimens, 
and has very rusty underparts. 
MUS MANDUS, new species. 
Type.—Skin and skull of adult male, Cat. No. 144225, U.S.N.M., 
collected at Sungei Mandau (tributary to the Siak River), eastern 
Sumatra, November 23, 1906, by Dr. W. lL. Abbott. Original number 
4898. 
Diagnostic characters.—A large member of the J/us asper group, 
differing from typical asper in its larger size, darker upperparts, and 
oray underparts. 
Color.—Type: Upper parts of head and body, a mixture of ochra- 
ceous-buff and brownish black, the latter color much in excess; sides of 
head, neck, and body, a mixture of the same two colors but in about 
equal proportions. Underparts gray, about like Ridgway’s No. 10 
eray. Hands and feet whitish; outside of legs similar to sides of 
body; inner side of the same color as underparts of body. Tail, 
bicolor, dark brownish above, whitish beneath. 
