SINCLAIR: TYPOTHERIA OF THE SANTA CRUZ BEDS. 89 
antero-posteriorly and transversely, but decreasing in concavity anteriorly, 
so that the palatal floor of the rostrum is practically flat. The anterior 
palatine foramina, as already described, are proportionately longer than 
in Hegetotherium , extending posteriorly beyond the premaxillo-maxillary 
suture. The posterior palatine foramina are in advance of the maxillo- 
palatine suture, perforating the maxillary opposite the anterior part of M-. 
The posterior narial border is divided by a strong median spine, as in 
Hegetotherium. In structure, the pterygoid region is practically the same 
in both genera, the only difference of importance appearing in the absence 
of the squamosal process, which in Hegetotherium is applied externally to 
the external alisphenoid plate (text fig. 1 6, page 74). The bullae are 
heart shaped, pointed anteriorly, but considerably flatter inferiorly than in 
Hegetotherium. The meatus is long, tubular and directed posteriorly, 
opening on a level with the postglenoid fossa. 
The distribution of the cranial foramina is similar to that in Hegetothe- 
rium. The infraorbital foramen opens into a deep fissure within the orbit 
connected by various vacuities with the olfactory chamber. Owing to the 
rupture of the thin interorbital septum in all the specimens in which this 
region is exposed, it is impossible to locate the position of the foramina 
opening at this point, but it is probable that a confluent foramen rotundum 
and spheno-orbital foramen and a large spheno-palatine foramen would 
be found to be present, as in Hegetotherium. An irregular opening at the 
anterior margin of the bulla marks the position of the foramen ovale and 
lacerum medius. The internal carotid enters the skull between the basi- 
occipital and the bulla near the suture between the basioccipital and the 
basisphenoid. The condylar foramina are rather large and are situated 
close to the condyle, while farther forward several additional foramina on 
either side perforate the basioccipital. The foramen lacerum posterius is 
inconspicuous, lying back of the bulla near the base of the paroccipital 
process. The presence of a postglenoid foramen cannot be definitely 
ascertained, owing to fracture in all specimens in which this region is 
exposed. ' Above the fossa for the tip of the stylohyal a pair of foramina, 
probably vascular, emerge at the edge of the auditory meatus. On the 
occipital surface the mastoid foramen occupies its usual position at the 
point of greatest transverse constriction of the occipital plate. 
The mandible (PI. X, figs. 1, 13) differs from that of any other genus 
of Santa Cruz Typotheria in transmitting an external branch of the inferior 
