On new Forms of Dendiomus, Dipodillus, dsc. 59 



Plate VI. 



Fig. 32. Transverse section of the opercular stalk (now shaped like a 

 cocked hat) after the lateral ridges have appeared. The great 

 development of the modified liypoderrn (hpi.) is conspicuous. 

 n., nerves ; bt., basement-tissue, which is highly developed. 

 X oc. 4, obj. A. 



Fig. 33. Oblique section of the distal end of the operculum, showing on 

 the right the presence of the ridge and on the left a reticulated 

 aspect of the region beyond after decalcification, x oc. 2, 

 obj. A. 



Fig. 34. Oblique section of the tip of the tail of a mature female speci- 

 men, ov., ova ; vm., ventral longitudinal muscles ; ao., external 

 aperture of the modified segmental organ; d., anus. The 

 canal is richly ciliated in this region, x oc. 2, obj. A. 



Fig. 35. Transverse section of the oesophageal region, with its thick 

 mucous lining internally, its chloragogenous coat (chl.) exter- 

 nally, with its plexus of blood-vessels (bv.). dv., dorsal blood- 

 vessel, x 280 diam. 



II. — JSew Forms 0/ Dendiomus, Dipodillus, and Gerbillus. 

 By Oldfield Thomas. 



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



Dendromus (Poemys) exoneratus, sp. n. 



Closely allied to D. nigrifrons of East Africa and Uganda, 

 but larger and with whitish ear-patches. 



General colour as in nigrifrons, but the blackish frontal 

 patch and the dorsal line less developed. At the anterior 

 base of the ears, just, in front of the base of the proectote, 

 there is a pair of whitish patches, each about 3 nun. in 

 diameter, which throw up by contrast the blackish frontal 

 patch. These whitish patches are found in all the six 

 specimens from Nigeria available, and in none of those from 

 Uganda and British East Africa. 



Skull decidedly larger than that oi 'nigrifrons. 



Dimensions of the type (measured in flesh by collector) : — 



Head and body 61 mm.; tail 71; hind foot 18; 

 ear 13. 



Skull: greatest length 21'3 ; condylo-incisive length 19; 

 zygomatic breadth 10*5 ; interorbital breadth 3; breadth of 

 brain-case 9' 7 ; palatal length 8'7 ; upper molar series 3*2. 



