G. GENER^VL NATURAL HISTORY AND ZOOLOGY. 303 



(Owen), (r. {Schist02yleurum) asper (B.), G. {Schistojyleurum) 

 dongatus (B.), and G. (Schistojyleimon) Icevis (B.). 



All these species attained a large and even gigantic size, 

 Borae having been about twelve or fifteen feet long. In ex- 

 ternal appearance, though true mammals, they had much re- 

 sembtance to tortoises. 



All the known species have been found in the later ter- 

 tiary beds of the Argentine Republic and contiguous ter- 

 ritory. 



IXTEEXATIOXAL EXPOSITION OF HORNS. 



Circulars have been issued by Captain Grant, of London, 

 looking forward to an exhibition in that city, on the 1st of 

 May, 1874, of a collection of the skulls and horns of the hollow- 

 horned ruminants, such as oxen, goats, sheep, and antelopes; 

 the object being to bring together as large a collection as 

 possible, with a view of showing the variations in size and 

 structure of each species, and the absolute number in public 

 or private museums. Captain Grant estimates that there are 

 fifteen species of the group known in Europe, thirty-nine in 

 Asia, eighty-nine in Africa, and eight in America, or one hun- 

 dred and fifty in all, and it is desired to have from twenty to 

 fifty specimens of each species exhibited. 



The collection is to be classified and grouped by competent 

 authorities, and marked with the names of those who shot or 

 exhibited them. Preliminary to the exhibition, the circular 

 lias been widely distributed throughout Europe and America, 

 in order to secure a list of specimens available for this pur- 

 pose. A blank page is provided, to be filled out, with head- 

 ings referring to the name of the animal, the exact latitude 

 and longitude where shot, found, or bred, sex, age, length of 

 horn along the curve, distance between the tips, circumfer- 

 ence, and whether the skull is attached or not. 



Should this exhibition prove to be satisfactory, it is pro- 

 posed hereafter to have another of the solid horns of animals, 

 such as those of the elk, deer, and even the rhinoceros. 



FOSSIL BLACK-HEADED DUCK IN BELGIUM. 



Professor Yan Beneden announces the discovery of re- 

 mains of a fossil bird in the Rupelian clay of the tertiary of 

 Holland, and identifies them unhesitatingly as belonging to 



