360 The American Geologist. May, 1894 
12H 2*»- Sulfoborite is Ihe first representative <>l' ;i new »roup of natur- 
al compounds of borates and sulphates, whicl! has an analogue in liine- 
burgite, a hydrous compound of magnesium borate with phosphate of 
magnesium. <i 
CORRESPONDENCE. 
Discovery of Diceratherium, the two-horned Rhinoceros, in the 
White River beds of Sooth Dakota. Several years ago Prof. Marsli 
described under the generic name of Diceratherium .a two-horned Rhi- 
noceros from the John Day beds of Oregon. Naturally we should ex- 
pect to find the ancestor of the John Day form in the White River beds; 
but up to the present.it has not been reported. The Princeton Scientific 
Expedition of 1894 has been fortunate in securing three skulls which at 
present are not distinguishable generically from Diceratherium. One 
of these skulls has been freed from the matrix and it presents charac- 
ters which at once distinguish it from any of the John Da.v species yet 
described. It may b< j called Diceratherium proavitum in reference 
to its relation to the John Day forms. 
The type specimen consists of a nearly complete skull without the 
lower jaws. The principal specific characters are as follows* Skull 
long and low. broad especially in the frontal region; superior surface 
slightly concave anteroposteriorly; no well denned sagittal crest; strong 
postorbital processes. Nasals strong but not coossified. About one-third 
thi' distance from their extremities to their junction with the frontals 
an- developed upon their upper and outer edge a pair of rugose promi- 
nences resembling very much in appearance the rugosities supporting 
the nasal horns of the recent rhinoceroses; they doubtless served the 
same purpose in Diceratherium. Just behind this pair of rugosities 
tin' nasals are constricted, but posteriorly they expand again to meet the 
broad anterior border of the frontals. In front of the pair of rugose 
elevations which supported the horns the nasals narrow rapidly and are 
directed downward and forward. The occipital crest is deeply emargi- 
nate and overhangs the occipital condyles. The zygomatic arches are 
rather slender. The post-tympanic and post-glenoid processes are in 
contact but not coossified. The anterior opening of the posterior nares 
is situated just behind the posterior border of ihe molar one. Of the teeth 
only the molars and premolars are preserved in the type specimen ; 
they are of moderate size. The premolar one is a strong, well developed 
tooth: the other teeth gradually increase in size from before backward. 
The dorsum is very flal with no suggestion of a median costa. There 
is a basal ridge on tin- dorsum of the true molars, but not on the pre- 
molars. The median sinus is shallow, especially in the premolars and 
molar one : it is obstructed by onh faint rudiments of the crochet and 
anticrochet. The anterior and posterior valla are shallow. There is a 
cingulum on the inner border of the premolars only. 
