44 ODOB^ENUS ROSMARUS ATLANTIC WALRUS. 



ment of course greatly increase with age, and vary considerably 

 in respect to direction, position, and relative development in 

 different individuals. The bony crests at the junction of the 

 interniaxillaries below the anterior nasal opening are especially 

 variable with age, becoming gradually obliterated in adult life 

 by the general thickening of the bones of the skull. They are 

 certainly less prominent in old age than in youth, and the same 

 is true of the incisive border of the intermaxillaries. The in- 

 termaxillaries, as a rule, only meet the nasals in their upward 

 extension, but in occasional specimens there is a narrow exten- 

 sion of them posteriorly between the nasals and maxillaries, 

 reaching for one-half to two-thirds the length of the nasals. 

 This variation is seen in the skulls figured by Goethe* and by 

 Blainville,t and has been noted in two skulls by Stannius.j: In 

 other cases the intermaxillary rises to the surface between the 

 nasals and maxillaries only in the form of narrow isolated areas, 

 as is seen in a skull figured by Goethe, and in two skulls I have 

 myself examined. Hence Blainville, when he says, " . . . . et 

 le premaxillaire, epais, remonte jusque entre le nasal et le 

 rnaxillaire, de maniere a circonscrire avec le premier Porifice 

 nasal . . . . ,"|| describes the exceptional instead of the normal 

 condition. 



The nasals vary greatly in breadth and in length in different 

 specimens, and even in the same specimen one is sometimes 

 much wider than the other. The concavity and width of the 

 bony palate is also subject to much variation, in this respect 

 hardly two specimens being found to agree. In some, the con- 

 cavity is nearly one-fourth greater than in others. 



*Act. Acad. Caes. Leop. Carol., xi, pt. i, pi. iv, fig. 2. 



t Oste"ograpbie, Des Pboques, pi. i. 



JSays Stannius: "Bisweilen aber, wie bei den Kieler Scbadeln a und c, 

 tritt nocb eine diiime Leiste dieses Fortsatzes zwischen die das Oberkiefer- 

 bein und das Nasenbein verbindende Langsnaht und trennt eine Strecke weit 

 diese Knochen. So siebt man es aucb auf der in dem Blainville'scben Werke 

 befindlicben Abbildung. Indem diese Leiste an einigen Stellen starker, an 

 .andern Stellen weniger stark oder gar nicbt nacb aussen bervortritt und zu 

 Tage kommt, bat es bisweilen den Anscbein, als fanden sicb isolirte Knocben- 

 stiickcben in der eben genannten Nabt. "Wirklicb erwabnt de Fremery eines 

 zwischen Nasenbein und Oberkieferbein vorkommenden Ossiculum Wormi- 

 anum bei seinem aus Labrador stammenden Walross-Scbiidel." 

 Archiv fur Anat., 1842, p. 401. 



Act. Acad. Cses. Leop. Carol., Bd. xv, pt. i, 1831, pi. iv, fig. 1. 



|| Ostdograpbie, Des Pboques, p. 20. 



