OCR Text |
Show 1882.] SPECIES OF HYPEROODON. 393 and the foramen magnum and the condyles are considerably smaller, as seen by the following dimensions :- H.planifrons. H. rostratus. millim. millim. Height of supraoccipital, from upper margin of foramen magnum to top of occipital crest 375 310 Width of supraoccipital, at narrowest part between hinder margins of temporal fossae .. 375 432 Width of foramen magnum 68 83 Width of condyles 212 257 Height of condyle 153 192 Fig. 1. JflsF * W till Jlillil -3.T WM-mSiWm^^^1-- -S Upper surface of cranium of Hyperoodon planifrons. In the upper surface (fig. 1) the want of bilateral symmetry in the region of the blowholes is extremely marked. The two characteristic prominences overhanging the anterior apertures to the nares, formed by the posterior ends of the prsemaxillae, with the nasals flanking their inner and the maxillae their outer surface, are larger and more massive than in Hyperoodon rostratus, especially the right one. The groove between them is narrower. The septum between |