2 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.61. 



On account of the early coosification of nearly all the bones in the 

 basicraniiun and the obliteration of the sutures, it is usually difficult 

 in adult skulls to determine their margins and relations. This slcull 

 (Cat. No. 10300, U.S.N.M.) belonged to an immature individual and 

 fortunately some of the sutures are still visible. Most of the fossil 

 genera allied to Megaptera are based either upon mandibles or verte- 

 brae, and since this form is known only from a skull no comparisons 

 are made with any of the previously described forms. It is by no 

 means certain, however, that some of the previously proposed genera 

 allied to Megaptera are valid, and in this connection attention is di- 

 rected to the two following closely related, if not identical genera: 

 Megajyteropsis rohustus ^ was proposed by Van Beneden for a mandi- 

 ble found at Wyneghem, Belgium, while a nearly complete vertebral 

 column from Antwerp was designated by the same author as the 

 type of Burtinopsis similisJ' These two genera were considered by 

 Herluf Winge ^ to be identical with the genus Megaptera. 



The discovery of this Miocene member of the Mystacoceti gives ad- 

 ditional force to the views of those who have advocated the great 

 antiquity of the Cetacea. It is now evident that a highly specialized 

 humpback whale existed during the Lower Miocene off the Pacific 

 Coast of North America, which affords further evidence for assum- 

 ing that the evolution of the Cetacea has taken a longer period than 

 has heretofore been considered plausible because of certain anatomi- 

 cal characters possessed by the living cetaceans.^ Along this line 

 there is considerable evidence from the structure of the periotic 

 which, although not conclusive, is at least strongly suggestive. It is 

 stated by Gray " that " in both the Cetacea and the Sirenia the coch- 

 lea is of a very primitive type." Further study of the auditory appa- 

 ratus of whales may reveal some interesting evidence bearing on the 

 antiquity of these forms. 



Megaptera miocaena is based upon an incomplete skull in which 

 the anterior half of the rostnmi and part of the right side of the 

 skull were cut off and lost, the block containing that portion having 

 been carted off to the brick plant before the true nature of the find 

 was fully known. The ventral surface of the skull is crushed in 

 across the palatal region, and some of the thinner bones are so brittle 

 and soft that they disintegi-ated during shipment from the field 

 to Washington. 



«Van Beneden, P. J., Bull. Acad. Roy. Sci. de Belgique, ser. 2, vol. 34, p. 15, Brussels, 

 1872. 



'Idem, pp. 19-20. 



* Winge, H., Vldensk. Meddel. fra den naturhist. Foren. i Kj0benhavn for 1909, pp. 1-38, 

 1910. 



•Weber, M., Die Saugetiere, pp. 126, 562, 571, 580-582, Jena, 1904. 



»<> Gray, A. A., The labyrinth of animals, vol. 2, pp. 22-23, London, 1908. 



