. Bulletin - United States National Museum. Science. 180 UNITED STATES NATIONAL MUSEUM BULLETIN 2 47 temporal fossa to the extremity of its zygomatic process. This slender zygomatic process is directed obliquely outward and forward to or almost to the end of the postorbital projection of the supraorbital process. The lambdoidal crest is continued forward on the dorsal edge of the zygo- matic process. at their extremities the exoccipitals on skulls of the immature individuals (fig. 79) are largely concealed from a dorsal view; the occipital condyles project backward beyond the level of
. Bulletin - United States National Museum. Science. 180 UNITED STATES NATIONAL MUSEUM BULLETIN 2 47 temporal fossa to the extremity of its zygomatic process. This slender zygomatic process is directed obliquely outward and forward to or almost to the end of the postorbital projection of the supraorbital process. The lambdoidal crest is continued forward on the dorsal edge of the zygo- matic process. at their extremities the exoccipitals on skulls of the immature individuals (fig. 79) are largely concealed from a dorsal view; the occipital condyles project backward beyond the level of the ends of the exoccipitals. On skulls of older individuals (fig. 77) the exoccipitals project back- ward beyond the level of the articular surfaces of the occi- pital condyles. The trans\'erse diameter (250 mm.) of the triangular occipital shield on the largest skull (USNM 16119) at the level of the dorsal rim of the foramen magnum. Figure 80.—Posterior view of skull (type), USNM 10668, of Parictobalaena palmeri Kellogg. For abbreviations, see figure 79. exceeds the greatest distance (195 mm.) from the dorsal rim of this foramen to the apex of this shield. On another skull (USNM 23022) these measurements are, respectively, 220 and 190 mm. The transverse diameter of this supra- occipital shield is progressively reduced above the middle of its height to the apex. Posterior view.—The ratio of height to the width of the braincase diminishes with growth and the exoccipitals become extended farther laterally. Depression of the top of the braincase increases with age. The broad supraoccipital constitutes the major portion of the triangular shield which curves upward and forward. On the cranium (USNM 10668; fig. 80) of the young whale this shield from a posterior view appears more rounded than it is actually. The lainbodidal crest (fig. 81) constituted by the lateral margins of the supraoccipital and exoccipital and the abutting edges of the parietals and squamosals, increases in
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