34 CETACEA. 



anterior extremity of the tympanic is pointed and the inner surface 

 more convex than in the last species. 

 JJab. Europe (Belgium, and England). 



M. 3533. The imperfect right tympanic ; from the Antwerp Crag. 

 This specimen agrees precisely with the one figured by 

 Van Beneden in the ' Aim. Mus. II. Hist. Nat. Belg.' vol. vii. 

 pt. 3, pi. xcvii. figs. 1, 2, and also in form with the 

 tympanic of M. boops (B.M. No. 1408 c). 



By exchange with the lloyal Brussels Museum of 

 Natural History, 1886. 



M. 3532. Cast of the slightly imperfect left tympanic of a somewhat 

 older individual. The original was obtained from the 

 Coralline Crag of Suffolk, and is preserved in the Ipswich 

 Museum ; it is described and figured by the present 

 writer in the ' Quart. Journ. Geol. Soc.' vol. xliii. p. 11, 

 pi. ii. figs. 5, 5 a. The specimen closely resembles the 

 one figured by Van Beneden, op. tit. figs. 9-11, and also 

 an old tympanic of M. loops in the' British Museum (No. 2. 

 76. 16. 18). Made in the Museum, 1886. 



Genus BAL^ENOPTERA, Laceptde 1 . 



The skull is small, the nasals are short and rounded, and the interval 

 between the frontal and occipital is comparatively short. The tym- 

 panic (woodcut, fig. 9) is moderately inflated, the inferior aspect 

 forminga comparatively narrow ellipse, which is scarcely wider behind 

 than in front ; the inner surface is flattened, without a vertical 

 groove ; the notch for the eustacliian canal is deep and sharply 

 defined ; the antero-inferior extremity of the inner surface is pro- 

 duced into a more or less well-marked ridge ; and the outer surface 

 of the involucrum is flattened ; the inferior surface has two ridges 

 corresponding to those of Meyopttra. 



Balaenoptera definita (Owen 2 ). 



Syn. BnJcena definita, Owen 3 . 



Balctnodon definita, Owen 4 . 

 Balanoptwa sMahtina, Van Beneden 5 . 



Hist. Nat. d. Cetaces, Table d. Orclres &c. p. xxxvi (1804). 



Proo. Geol. Soc. vol. iv. p. 283 (1843). Bulcena. 



Loc. tit. 



Bril . Foss. Mamm. and Birds, table facing p. xlvi (1846). 



Bull. Ac. E. Belg. ser. 2, ?ol. 1. p. 14 (I860). 



