ART. 26 EEMAIXS OF FOSSIL PORPOISES KELLOGG 15 



would readily become separated from the skull during decay or 

 before the skull was buried by sediments. Sixteen teeth are in place 

 on the right side of the rostrum and 33 teeth on the left. By count- 

 ing the vacant alveoli and the teeth in place, it appears that origi- 

 nally 59 teeth were present on the right side and 60 on the left 

 side. As by far the greater portion of the rostrum is constituted 

 by the maxillae, they will be discussed first. Near the anterior end 

 of the tooth row the external face of the maxilla is rounded, and in 

 front of the vomer it is nearly vertical, but at a point 190 mm. in 

 front of the maxillary notches the lower outer margin begins to 

 twist upward. This portion of the maxilla becomes progressively 

 thinner as it approaches the maxillary notches. Again it may be 

 noted (pi. 1) that no indication of sutures to mark the presence of 

 the premaxillae on the ventral surface of the rostrum can be traced 

 in this or in any of the skulls mentioned in another part of this 

 paper. Posteriorly the maxillae are separated for a short interval, 

 permitting the keel of the vomer to appear between them. Behind 

 this the maxillae are overlain by the palatines. The thin platelike 

 process of the maxilla that extends backward to the optic canal is 

 applied to the ventral face of the supraorbital process of the frontal. 

 The ventral orifice of the infraorbital canal is bounded by the max- 

 illa alone. In front of this orifice there is a shallow heart-shaped 

 depression which extends over the palatine and the maxilla for a 

 distance of 60 mm. in front of the maxillary notches. 



There is nothing peculiar about the position of the palatines. 

 They meet mesially and are closely appressed to the maxillae. 

 Viewed from the side, the palatine extends forward beyond the 

 maxillary notch and above the pterygoid projects backward to the 

 anterior margin of the optic canal. Close to its posterior extremity, 

 but above it, the palatine comes in contact with the orbitosphenoid. 



The jugal is a long, slender bone, consisting of a short, triangular, 

 dorso-ventrally expanded anterior portion which is closely joined 

 to the maxilla and lachrymal, and a styliform posterior process. 

 The posterior end of the latter is flattened and extremely thin, being 

 loosely attached to the ventral face of the zygomatic process. 



The lachrymal is closely appressed to the anterior face of the 

 supraorbital process of the frontal and is sheathed dorsally by the 

 maxilla, while internally it appears to be fused with the jugal. In- 

 asmuch as no suture can be found it should be stated that these com- 

 bined bones occupy the lower margin of the maxillary notch. 



Some confirmation as to the true relations of the pterygoids with 

 the surrounding bones appears to be found in certain living por- 

 poises. By studying the relations of the various bones involved in 

 this and other skulls hereinafter mentioned it was apparent that the 

 type of structure present was essentially in agreement with that of 



