TOXOCHELYID. 183 
The skull is broad and it was probably originally considerably deprest, but to what extent 
the present flatness is due to pressure can not be determined. The outlines as seen from above 
(fig. 235) are greatly like those of Porthochelys laticeps, but the skull of the present species 
is longer than broad. The sides of the skull converge slowly to the front of the orbits, where the 
width is still 100 mm., then rapidly approach the tip of the snout. The outline is such that the 
snout appears somewhat produced. The occipital condyle is broken away, but from its esti- 
mated position to the end of the snout is 160 mm.; from the end of the supraoccipital spine to 
the snout, 190 mm. The breadth from the outside of one quadrate to that of the other is 142 
mm. The bones of the upper surface of the skull are smooth, whereas those of P. latice ps are 
ridged and grooved. The temporal region is rooft over not quite as far backward as the 
hinder borders of the exoccipitals and paroccipitals, so that the latter bones are seen from above. 
Hence, the roof is not so extensive as in Chelonia mydas, but about as complete as in Caretta. 
Fic. 235.—Porthochelys brownt. Skull of type, upper aspect. 4. No. 6080 A. M.N. H. 
fr, frontal; ju, jugal; mx, maxilla; pa, parietal; pof, postfrontal; prf, prefrontal; sg, squamosal. 
The eyes of this turtle were evidently directed strongly upward as well as outward. The 
distance from the middle of the lower part of the rim of one orbit to that of the other is go mm. 
The width of the interorbital space is 30 mm. If now the middle of the interorbital space 
stood 50 mm. above the roof of the mouth the plane of the orbits would stand at an angle of 
45° with the horizontal. It is not probable that the elevation of the skull was greater than that 
supposed. The longitudinal diameter of the orbit is 50 mm. The transverse diameter of one 
is now 33 mm., of the other 30 mm. If the elevation of the skull was originally 50 mm. above 
the roof of the mouth the transverse diameter of the orbit must have been about 43 mm. It 
is not likely to have been more. Hence, we seem to be justified in believing that the eyes were 
directed strongly upward. 
It is evident that the nasal opening was higher than wide. Its present width is 19 mm., its 
height 21 mm. The distance from the orbit to the hinder border of the temporal roof is 53 mm. 
The anterior borders of the choanz are placed 43 mm. behind the tip of the snout (fig. 236). 
The palatines appear to have joined the vomer, as in Toxochelys. The crushing-surtaces of 
the upper jaws have a width of about 27 mm. They are concave from the cutting-edge of the 
jaw to the palatines. The width of the combined pterygoids, where narrowest, is 39 mm. 
