167—80 CRANIA OR RUMINANTS FROM THE INDIAN TERTIARIES. 
enormously, the bases of the horn-cores being separated by a long interval from 
each other, and closely approximated to the orbits ; in Sydaspitherium, on the other 
hand, the skull has a long and deep contraction above the orbit, and is not wider 
at the base of the horns, which have a common origin, than at the orbits, while 
the base of the horns is separated by a long interval from the orbit ; the larger horns 
of SivatJierium were mainly directed outwards, while the direction of those of the 
new genus was probably at first nearly vertical ; the nasals of the latter genus were 
longer and not arched or pointed like those of Sivatherium. Owing to the position 
of the posterior horns, the temporal fossa of Sivatherium forms a comparatively 
narrow slit not wider than the orbit, and completely overarched by the base of the 
horn ; in the cranium of Sydaspitherium, on the other hand, the temporal fossa 
is very wide, and quite open above. On the palatal aspect the cranium of Sivathe- 
rium is wider in proportion to its length than is the cranium of Sydaspitherium, 
while the space enclosed by the zygomatic arch has its transverse diameter longer 
than its antero -posterior diameter, the reverse being the case in Sydaspitherium. 
The form of the basi-occipital and sphenoid is nearly the same in both genera, 
but the anterior tubercles of the former bone are relatively much larger in the 
new genus ; the line of the molars is more curved in Sivatherium ; the occiput 
is relatively wider in the latter genus, while the depression for the ligamentum 
nuchge approaches nearer to the foramen magnum, and the temporal fossae are 
seen as large slits on the occipital surface, while they scarcely show in Sydaspi- 
therium. 
In the following characters the three alhed genera agree, viz., the presence of 
horn-cores on the upper part of the frontal ; the general form of the teeth, which 
are coated with a rugose enamel; the great width of the posterior half of the 
base of the cranium ; the elongated and wedge-shaped basi-cranial axis ; the pre- 
sence of two pairs of tubercles on the basi-occipital, of which the hindmost are 
small ; the form and position of the free border of the palatines, and the direction 
and position of the orbit ; the approximate parallelism of the basi-cranial axis and 
the palate. 
In the Memoir quoted above, Dr. Murie lays great stress on the form and 
relations of the nasals, as connecting Sivatherium with Saiga ; this, on the face of 
it, appears to me a very insignificant character, and is also one which, as stated above, 
is not borne out by the present genus, in which the nasals are connected with the 
maxiRse ; as showing the slight value of this character, I may refer to a new 
Turkestan sheep, Ovis harelini of Severtgoff,’ in which the nasals do not articulate 
with either the maxiUse or premaxillse, as in Saiga, and yet no one would think of 
classifying the two together: the unimportance of the character in the Bovidce 
was also noticed in an earlier portion of the present Memoir. From the form 
of its posterior horns Dr. Murie argues with more probability that Sivatherium 
was also related to Antilocapra ; he, however, to a great extent ignores its relation- 
^ Ann. Mag. Nat. Hist., Ser. 4, vol. xviii. p. 210. 
