16 



CETACEA. 



Older CETACEA. 

 Suborder MYSTACOCETL 



Functional teeth are wanting and the jjalate is provided with 

 baleen ; the cranium is symmetrical ; tlie nasals form a roof to the 

 narial passages ; and the tympanic is involuted and anchjdosed to 

 the periotic. 



Family BAL.ENIDiE. 



This family includes all the members of the Suborder. 



A. — Bal^nine Section. 



At least usually, some or all of the cervical vertebrae are anchy- 

 losed together. The tympanic is deep and angular, its inflation 

 comparatively slight, the involucrum^ not fig-shaped, and frequently 

 with no well-marked depression at the anterior extremity of the 

 superior border of the inner surface for the eustachian canal. 



Genus BAL^SSNA, Linn.' 



Including Bal(27iula, Van Beneden '^. 

 Balcsnotus, Van Beneden "*. 



Balmna mysticetus. — The right tympanic of an immature individual, from the 

 inner (A) and outer (B) aspects ; recent. ^. (From the ' Proc. Zool. See.') 



^ This terra may be applied to the reflected superior portion of the inner wall 

 of the bone. 



2 Syst. Nat. ed. 12, vol. i. p. 105 (1766). 



3 Bull. Ac. E. Belg. ser. 2, vol. xxxiv. p. U (1872). 

 * Ibid. p. 13. 



