28 



Christmas Island. 



Measurements of the specimens obtained are given below : — 





Head and B 



3dy. 



Tail. 



Ear. 



Hind-foot 



$ 



72 mm. 





75 mm. 



7i 



mm. 



15 mm. 



$ 



... 65 „ 





68 „ 



7 





16 „ 



s 



... 76 „ 





72 „ 



. 10 





... 17 „ 



$ 



... 73 „ 





74 „ 



. 10 





16 „ 



$ 



... 79 „ 





73 „ 



8 





15 „ 



$ 



... 70 „ 





65 „ 



9 





15 „ 



? 



... 67 „ 





63 „ 



7 





... 14 „ 



$ 



... 78 „ 





70 „ 



8 





13 „ 



$ 



... 82 „ 





72 „ 



. 11 





16 „ 





... 70 „ 



y.^■c ^-P 



63 ,, 



9 





.. 15 „ 



Head and body, 70 mm. ; tail, 80 mm. ; hind-foot, 16 mm. 



This little animal is extremely common all over the island, and 

 at night its shrill squeak, like the cry of a bat, can be heard on 

 all sides. It lives in holes in rocks and roots of trees, and seems 

 to feed mainly on small beetles. 



4. Mus nativitatis, Thomas. (Plate II.) 



P.Z.S., 1888, pp. 533-4. 

 IVIr. Thomas's description of this species is given below : — 



«• & (type) • 

 b.^ . . . 



Head 



and 



Body. 



Tail. 



Hind- 

 foot. 



Forearm 



and 



Hand. 



Ear. 



Heel to 



front of 



last footpad. 



mm. 

 254 



264 



mm. 

 176 



175 



mm. 

 54 



54 



mm. 

 66 



65 



mm. 

 20x17 



18x17 



mm. 

 26-6 



27-3 



" Skull : Basal length 46*8, greatest breadth 24'8 ; nasals, length 

 20*5; interorbital breadth, 8'7 ; intei'parietal, length 7*1, breadth 

 12*5 ; infraorbital foramina, length of outer wall 4*1, breadth 

 from outer corner of one to that of the other 13*4 ; palate, length 

 26*7, breadth outside m.^ 9*0, inside m.^ 4*5; diastema, 15*5; 

 length of anterior palatine foramina, 9*3 ; length of upper molar 

 series, 7*6. Lower jaw, length (bone only) 30, (to incisor-tips) 

 34*6 ; greatest height, obliquely, from coronoid to angle, 15. 



' ' Size large ; form thick and clumsy, the limbs and tail stout and 

 heavj^ but the head peculiarly small, slender, and delicate. General 

 colour dark umber-brown all over, the belly not or scarcely 

 lighter than the back. Ears small, laid forward they barely reach 

 to the posterior canthus of the eye. Fur of back, long, thick, and 



