AKT. 14. THE SKULL OF MEGAPTEEA MIOCAENA KELLOGG. 5 



and the zj'goma has been restored on plate 2 from a recent Megaptera 

 nodosa. No trace of an alveolar gutter for rudimentary teeth can be 

 found along the lateral margin of the maxilla. 



PREMAXILLAE. 



The premaxillae are more slender than Megaptera nodosa, but are 

 otherwise closely similar so far as can be determined from the frag- 

 ments which were preserved with the skull. Posteriorly these bones 

 send back long facial processes, which are lodged in grooves on the 

 upper internal margins of the maxillae, as well as in deep paired 

 grooves on the anterior margin of the combined frontals. The pre- 

 maxillae are bent downward internally as they approach the nasals, 

 being closely appressed to the maxillae, and form in this region the 

 lateral borders of the nasal openings. 



In most respects the nasal is similar to that of Megaptera nodosa. 

 It is short in proportion to the length of the rostrum, concave from 

 side to side, and curves ventrally. The free extremity of the nasal is 

 slightly expanded and abruptly truncated. The paired nasals form 

 the posterior border of the nasal openings. 



FRONTALS. 



The frontals are much reduced in extent on the vertex, being over- 

 ridden by the supraoccipital posteriorly and the maxillae and nasals 

 anteriorly. In a middle line in front the combined frontals send for- 

 ward a wedge-shaped process which separates the nasals posteriorly, 

 and on the left side external to this process there are present two deep 

 grooves, separated by a thin septum, for lodging the posterior end of 

 the premaxilla. Laterally the frontals suddenly widen out to form 

 broad and massive supraorbital processes, though at a lower level 

 than the vertex, and afford complete osseous roofs for the orbits. The 

 supraorbital process slopes forward ; its posterior margin is greatly 

 thicliened and curves sharply downiward at right angles to the roof. 



Ventrally the preorbital and postorbital processes are prolonged 

 downward in a gentle convex curve inclosing the optic fossa. The 

 postorbital margin of the supraorbital process is prolonged into a 

 thin ventrally directed plate, though it apparently did not meet 

 the blunter and similarly directed plate of the preorbital margin to 

 arch over completely the optic fossa. A further difference from 

 Megaptera nodosa lies in the exposure of the optic surface of this 

 element for its whole extent, even though there is a conspicuous over- 

 rolling on the part of both preorbital and postorbital plates, with the 

 result that the orbital roof is reduced to a narrow triangle on the 

 external half. Tlie descending process of the frontal, a continuation 

 of the preorbital plate, does not abut against the external pterygoid. 



