MAMMALS OF ANGLO-EGYPTI.\N SUDAN — SETZER 507 



dyloincisive length of skull 34.7; crown length of upper toothrow 7.2; 

 length of anterior palatine foramina 7.9; greatest width across zygo- 

 matic arches 19.6; least interorbital width 4.8; length of nasals 12.6; 

 width of rostrum at level of antorbital foramen 4.1. 



Comparisons: From Dasymys incomtus helukus, D. i. palustris 

 differs in lighter color, that is, more red and less yellow and brown, 

 and belly with no buff}^ wash as in helukus. Skull is smaller, auditory 

 bullae smaller, rostrum shorter, upper cheekteeth smaller, least inter- 

 orbital width greater, and nasals sliorter. 



D. i. palustis differs from D. i. nigridus in the same manner as from 

 D. i. helukus and is even markedly lighter in color. 



From D. i. savannus, D. i. palustris differs in having no buffy wash 

 on the belly and in having a small skull, markedly smaller auditory 

 bullae, shorter rostrum, and shorter nasals. 



D. i. shawi differs from D. i. palustris in darker color, smaller audi- 

 tory bullae, and longer anterior palatine foramina. 



D. i. palustris differs from D. orthos in having a longer tail, generally 

 redder color, and lacking the olivaceous wash on the belly. The skull 

 has a narrower rostrum, smaller, more elongate, less inflated auditory 

 bullae, more flaring zygomatic arches, shorter nasals, narrower inter- 

 orbital region, markedl}^ larger and longer anterior palatine foramina, 

 and the anterior edge of the zygomatic plate being concave instead of 

 relatively straight as in orthos. 



Remarks: I am inclined to agree with EUerman that the former 

 species of Dasymys are in reality only one species with an infinite 

 amount of variation. This probably includes even orthos, but until 

 such time as the significance of the straight anterior edge of the 

 zygomatic plate is understood it is probably better to treat that 

 species as such. Certainly, in all of the specimens examined from 

 most of the range of the genus, that peculiarity is outstanding. 



From the material available it appears that orthos is not a part of 

 the fauna of the southern Sudan. 



Dasymys incomtus siiawi Kershaw 



Figure 6,a 



Dasymys shawi Kershaw, Ann. Mag. Nat. Hist., ser. 9, vol. 13, p. 25, January 

 1924. (Mount Baginzi, southern Bahr-el-Ghazal, near Congo border, 40 

 miles south-southeast of Yambio.) 



Specimens Examined: Two, both in BAI, from: 40 miles south- 

 southeast of Yambio, 1 ; Yambio district, 1 . 



Measurements: The type, an adult male, measures as follows: 

 Length of head and body 152; length of tail 144; length of hind foot 

 29; length of ear 19; condyloincisive length of skull 34.2; crown length 

 of upper tootlii-ow 6.6; length of anterior palatine foramina 7.6; great- 



