The brain case is small proportionately and rounded. The "face" is therefore long, and in some cases, especially among the fossil forms of Platanistidae, the rostrum is extraordinarily elongated. The asymmetry of the Whale's skull is one of its most remarkable features; this, however, is entirely limited to the Toothed Whales, and among them is more pronounced in some forms than in others. Thus the Platanistidae and many Ziphioids are not nearly so asymmetrical as the {350} Dolphins and, especially, _Physeter_. This asymmetry affects particularly the premaxillae, the maxillae, and the nasals. The base of the skull is symmetrical. The Whale's skull has very long premaxillae which, however, do not, except in the extinct Zeuglodonts, bear any teeth. The nasal bones, whether symmetrical or the reverse, are very small in existing Whales, which arrangement, together with the long and broad maxillary bones, removes the anterior nostrils, the blow-hole, far backwards. The roof of the skull is not at all formed by the parietals externally. These bones form a portion of the side of the cranium, but are replaced or covered by the {351} enormously-developed supra-occipital in the adult. Here again the Zeuglodonts are more typically Mammalian, for in them the parietals have a normal development and situation, rising even into a median crest as in so many quadrupeds. The bones related to the organ of hearing, the tympanis and petrous bones, are very solid and dense in structure. Moreover they are but loosely attached to surrounding bones, and are thus easily and frequently lost. Nearly the only mammals which resemble the Whales in the fact that the pterygoids sometimes meet in the middle line below are the Edentata (Anteater and Armadillo, see p. 167). But in both groups this peculiarity is not universal. [Illustration] FIG. 185.--A section of a skull of a young Caa'ing Whale (_Globicephalus melas_). x 1/5. _a_, Angle; _an_, anterior nares; _AS_, alisphenoid; _bh_, basihyal; _BO_, basioccipital; _BS_, basispnenoid; _cd_, condyle; _cp_, coronoid process; _ExO_, exoccipital; _Fr_, frontal; _id_, inferior dental canal; _IP_, interparietal; _ME_, ossified portion of the mesethmoid; _Mx_, maxilla; _Na_, nasal; _Pa_, parietal; _Per_, periotic; _Pl_, palatine; _PMx_, premaxilla; _pn_, posterior nares; _PS_, presphenoid; _Pt_, pterygoid; _s_, symphysis of mandible; _sh_, stylohyal; _SO_, supra-occipital; _Sq_, squamosal; _th_, thyrohyal; _Vo_, vomer. (From Flower's _Osteology_.)