ant. 16. TWO SQUALODONTS FROM MARYLAND—KELLOGG. 49 
The zygomatic process of the squamosal is slender, curved, and 
tapering anteriorly. The postglenoid process is thin, directed more 
downward than backward. The temporal fossa is quite large, with the 
superior margin formed by the frontal and the overlying maxilla. In 
either temporal fossa the parietal is suturally united inferiorly with 
the squamosal, anteriorly with the frontal, and superiorly is synos- 
tosed to the thick lateral margins of the supraoccipital, forming 
an apparently continuous surface. The parietals are thus excluded 
from the dorsal surface and from the vertex of the skull. 
A close examination of the surface of the cranium in the left tem- 
poral fossa shows a fissure in front of the squamosal and at its ante- 
riormost point of contact with the parietal. This fissure is partially 
filled in by a triangular wedgelike bone which is interpreted to rep- 
resent the ala temporalis or alisphenoid. The position of this bone 
and its relations to the surrounding elements correspond in all essen- 
tial details with the same element in the skull of a foetal Balaenop- 
tera in the United States National Museum. Unfortunately, the cra- 
nium on the right side is so badly broken in the region of the tem- 
poral fossa that no additional information can be obtained from that 
side of the skull regarding the relations of the alisphenoid to the other 
bones. In front of the parietal and above the aforementioned fissure, 
the frontal takes part in the formation of the lateral wall of the 
cranium. 
Viewed from the side the condyles project beyond the plane of 
the exoccipitals. Theskull has not been restored in the palatal region. 
The palatines and pterygoids, if present, would impart a slightly dif- 
ferent appearance to this part of the skull. 
Ventral view.—The basioccipital is a relatively narrow bone with 
ventral surface concave from side to side, and terminated posteriorly 
by the paired condyles. Anteriorly, it is synostosed with the basi- 
sphenoid. Thesides of the basioccipital are prolonged downward into 
free plates, which are characterized by convex swellings on internal 
and external sides. In this feature this skull (pl. 2) differs from the 
type of Squalodon bariensis.“% In the latter, the descending plates 
are reduced in extent and are much longer anteriorly than posteriorly. 
These plates in Squalodon bariensis also join the pterygoids in front, 
which are hollowed out inferiorly to form the palatine vacuities. A 
close examination of the skull of the squalodont from Maryland 
reveals features which might suggest a different type of architecture 
in the palatine region. Since the palatines and the pterygoids are 
completely missing from this specimen there is no opportunity for 
further comparisons. 
The descending plates of the basioccipital serve as the internal 
walls for the scaphoid fossa, the anterior and outer boundaries of 
73 Lortet, L., Archiv. Mus. d’Hist. Nat. de Lyon, vol. 4, pl. 25bis, 1887. 
