SCHULTE, SEI WHALE. 475 



foramen is divided by membrane into a mesal compartment for the nerves mentioned above 

 and a lateral one for the jugular vein. 



Norma verticalis. The norma verticalis differs from that of the adult not only in the short 

 and broad rostrum, but even more conspicuously in the broad and rounded form of the brain- 

 case and its great size as compared with the laterally projecting portions of the squamosal and 

 frontal. The interparietal is single, free, and of a pentagonal shape. The supra-occipital is in 

 contact with it caudad and is beginning to override its caudal margin, but only to a very slight 

 degree. Except at this border it is surrounded by a wide fontanelle of complicated outline, 

 which at the sides extends to the parietals and frontals, rostrad to the frontals which are in 

 sutural contact in the median line. The orifice of the nasal fossa is bounded as in the adult, 

 the nasal bones being short in proportion to their breadth; they are slightly expanded at their 

 free extremities. Their margins are sharp and slightly concave. The premaxillse, in corre- 

 spondence to the short rostrum, are less slender than in the adult, but otherwise are closely 

 similar. They are separated by a strip of cartilage, the dorsal margin of the cartilage of the 

 septum. The maxillae are more broadly triangular than those of the adult. Their nasal processes 

 ascend more vertically, in consequence of the greater convexity of the forehead, and their mesal 

 inclination is distinctly less. They are marked by a high transverse ridge near their articulation 

 with the orbital plate of the frontal, which marks the limit caudad of the origin of the deep 

 stratum of the transverse rostral muscle; the groove caudal to it, in which laterally the lachrymal 

 is seen, gives attachment to part of the occipitofrontalis and to the muscle arising from the 

 supra-orbital margin. The orbital plate of the frontal has a strong sagittal arch, and broadens 

 laterad to the supra-orbital margin. The postorbital process is slender and decurved, it is joined 

 to the zygomatic process of the squamosal by a quantity of fibrous tissue, to which is attached 

 on a more ventral plane the zygoma. The slenderness of these processes of the frontal and 

 squamosal and their small degree of lateral projection are among the striking differences of the 

 fcetal from the adult cranium. 



Norma basalis. The hard palate has nearly attained the adult conformation of its com- 

 ponent parts. The vomer is more exposed rostrad, where the maxillae abut upon it by a rounded 

 margin; in their caudal thirds they begin to cover it with their marginal plates. The palate 

 bones overlap it to a greater degree and eventually meet in the midline, leaving a small knob 

 of the ventral border exposed caudal to them. The maxilla has a wide alveolar sulcus in its 

 caudal half, which opens into a large cavity, in which are contained the dental anlages and which 

 the maxillary division of the quintal nerve enters from behind after passing ventral to the orbit. 

 Mesal to the alveolar region there is a sagittal concavity which becomes deepest in the region 

 where the horizontal plate of the palate is received between the mesal and lateral processes of 

 the maxilla. The lateral border of the maxilla is thick and convex, differing here in contour 

 as well as in proportions markedly from the adult. The caudal extremity of the maxilla was 

 very imperfectly ossified and covered by thick and strong periosteum, in the removal of which 

 the delicate caudal border was damaged. So far as could be ascertained this portion of the 

 >one was blunt and rounded and did not end in a thin sharp-edged plate, as in the adult, resem- 

 bling in this respect less modified types of maxillae. The orbital process is deeply grooved 

 between the alveolus and the orbital margin for the passage of branches of the facial nerve and 

 vessels to the dorsum of the rostrum. 



The horizontal plate of the palate requires no special comment; the vertical plate is short 



