99*2 DR. J. E. GRAY ON A NEW ATELES. [ DcC. I'i, 



In the Museum there is a specimen of an Emu's egg containing 

 the chick-bones at about the same stage of development. 



On comparing these two specimens, the principal difference con- 

 sists in the dense brittle character and white colour of the Emu 

 hones as compared with those of the Moa chick, and in the enor- 

 mous disproportion in the massiveness and form of the bones of the 

 extremities in the latter case, with the very slight difference in the 

 size of the cranium and total relative height of the embryos. 



The specific gravities of these bones are respectively — 



Moa chick 1 -538 



Emu chick l'l>77 



Bone of old Moa I'/OO to 1-979 



The comparative length of the principal bones of these chick-ske- 

 letons are as follows : - Moa chick. Emu chick. 



inches. inches. 



Cranium 2-1 20 



Pelvic bones 2-6 1 G 



Femur 17 12 



(Diameter of shaft -3;") in.) (Diameter of shaft '28 in.) 



Tibia 30 21 



(Diameter of shaft -35 in.) (Diameter of shaft • 16 in.) 



Fibula 2-0 15 



Tarso-metatarsus 1 "9 1'8 



Probable total length of Moa chick 14-5 inches. 

 Probable total length of Emu chick 130 inches. 



Weight of bones of extremities and pelvis — 



In the Moa chick IG7'0 grains. 



In the Emu chick 40-5 grains. 



Or in the proportion of 4 to 1. 



7. Description of Ate/es bartlettii, a New Spider Monkey 



from the lliver Amazons. By Dr. J. E. Gray, F.R.S., 



V.P.Z.S. &c. 



(Plate XLVII.) 



One of the most important zoological results of Mr. Edward Bart- 

 lett's exploring excursion up the River Amazons has been the disco- 

 very of a new Spider Monkey*, which differs from all the species of 

 this usually lugubrious genus in the brightness and beautiful dis- 

 position of its colours. Mr. Wolf has made a beautiful drawing of 

 this specimen, which is now ia the British Mviseum collection. 



Ateles bartlettii, sp. nov. (PI. XLYII.) 



Fur abundant, long, and soft. Black ; the cheeks white ; a band 

 across the forehead over the orbits bright reddish yellow ; the chest, 



* See Mr. Uartlett's notice of the discovery of this species, P. Z. S. 1867, p. 2. 



