324 
A MEMOIR UPON THE GENUS 
very much reduced and limited posteriorly, and the animal has a large proboscis. 
On referring to the Diuocerata, it is found that these animals have the nasal region 
constructed hi about the same way as in the recent Rhinoceros, with the difference 
that the nasals are prolonged beyond the premaxillary suture in Dtnoceras. T 
believe that they were without a proboscis, but probably had a very large and pre- 
hensile lip. I am led to this conclusion by the great posterior and vertical extent of 
the lateral nasal notches. Accepting the above data as probably establishing the 
presence of a proboscis, I conclude that Palceosyops megarhinus was without 
such an organ, because in this species, as in all others of this subfamily as far as 
known, the nasal bones are very largely developed and extend so far forward as to 
overhang the premaxillary region. The lateral nasal notches of P. megarhinus 
are deep, but not high, and probably for this reason the upper lip was not as pre- 
hensile as in the Rhinoceros. In Titanotlm'ium the nasal notches are larger and 
there was probably more freedom of motion in this region. 
Frontals.—^\\Q frontals are rather broad and short. They widen very much 
anteriorly, and have only a slight articnlation with the ascending processes of the 
maxillary. The articulation between the frontals and nasals is broad and extends 
across the Avhole forehead. The interorbital region of the frontals is rather 
broad, convex, and sends out long and acuminate lateral postorbital processes. The 
portion of the frontals forming the superciliary boixler of the orbit is thick and 
rounded off. The po.sterior part of the frontals forming the anterior portion of the 
temporal fossa is not strongly excavated and is bordered above by weakly developed 
anterior temporal ridges. 
Parietals . — The parietals unite along their whole superior extent to form the 
sagittal crest. The latter is high, strongly compressed, and arises from the upper 
third of the temporal fossa, thus forming the extremely high roof of the cranial 
cavity. At the junction of the parietals and squamosals the surface of the temporal 
fossa is strongly convex and shows a well marked bulging of the cranial cavity out- 
ward. In the skull of P. paludosus the whole surface of the temporal fossa is 
deeply excavated, showing a less development of the lateral masses of the cerebrum 
than in P. megarhinus. 
Occipitals . — The condyloid portion of the exoccipitals is strongly con- 
stricted off from the supraoccipital region, thus placing the foramen magnum 
widely back from the surface of the occiput. The jmrtion above the foramen mag- 
num is smooth and superiorly overhung by the well developed lambdoidal crest. 
These crests are well developed as far as the lateral parts of the occiput, 
and are proportionately larger in this region of P. megarhinus than in 
P. paludosus. The paroccipital processes have much less transverse extent in 
this species than in the larger form, and their exti-emities are more styliform. The 
condyles are broad and heavy, and their transvex’se extent is as great as in P. 
paludosus. Superiorly the condyles are separated by a wide and straight 
notch ; their infeidor extremities are prolonged upon the basioccipital and separated 
