816 The American Geologist. November, is97 
should expect to find the ancestor of the John Day form. 
When the latter beds shall have been as carefiillj' explored as 
have the White River beds there will doubtless be found a 
series of forms running gradually from I). proavifAini in the 
Protoceras beds to D. advenuni, Marsh in the John Day. The 
rugosities in the former species are, it is true, not nearly so 
prominent as in the latter, but they are in the proper posi- 
tion, and that they supported incipient horns is shown by 
every collateral character which we should reasonably expect 
to find in the White River ancestor of the John Day form ; it 
should therefore be considered as ancestral to that form. 
I present here for comparison in figs. 1 and 2 the sup. view 
of the type of I), pronvitum and a reproduction of Prof. Os- 
born's figure showing same view of A. tridactylnm. The ru- 
gosities on the nasals in the latter as shown by Prof . Osborn"s 
descriptions in the text and as stated b}' the draftsman are 
taken not from the type, but from anotlier skull, referred to 
the same species. In fig. 1 the broad nasals, entirely conceal- 
ing the premaxillaries, the position of the fronto-nasal suture 
and the low, short, broad sagittal crest are especially note- 
worthy as contrasting with the same characters in fig. 2. 
Fig. 1. Sup. view of type of D. proavitum (No. 10965) 1-5 uat. size. 
Fig. la. Cross-section of nasals immediately in front of horns, two- 
fifths nat. size. Drawn by R. Weber. 
Fig. 2. Sup. view of A. tridactylnm, 1-5 nat. size, after Osborn. 
Drawn by R. Weber. 
The principal distinctive characters of D. proiivitiim and A. tridacly- 
Inm may be tabulated as follows i 
D. proaintmn. 
Skull rather short, low and broad. 
Nasals very thick, broad, and with 
prominent rugosities on sup. sur- 
face. Frontonasal suture only a 
little in front of orbits. Sagittal 
crest broad, short and low, almost 
disappearing. 
A. tridcwtylum. 
Skull long, high and narrow. 
Nasals slender and i)erfectly smooth 
on sup. surface. Frontonasal su- 
ture situated well in front of or- 
bits. Sagittal crest high, long and 
narrow. 
THE FISHER METEORITE. 
CHEMICAL AND MINERAL COMPOSITION. 
T^y N. H. WiNCHELL, Minneapolis. 
For the purpose of further determination of the mineraf 
which resembles maskelynite, two micro-cliemical tests were 
made. The particles are so small that nochemical extuiiinatiou 
is practicable; viz.: 
