CETACEA. 63 



cmarginata may be said, therefore, to occur in the Nodule-bed 

 of the Red Crag of Suffolk, and in the Antwerp Crag. 



BAL^ENOPTERA, sp. 



A large vertebra from the Forest-bed near Cromer is 

 referred to this genus (Mem. Geol. Surv., Vert. Forest Bed, p. 

 108, 1882, and Quart. Journ. Geol. Soc., Vol. XLIL, p. 322, 

 1886) and indicates a form as large as a full-sized Fin Whale 

 (B. musculus). 



Genus CETOTHERIUM, Brandt. 

 CETOTHERIUM (PLESIOCETUS) BRIALMONTI, v. BENEDEN. 



The genera Plesiocetus and Heterocetus of Van Beneden (Bull. 

 Ac. Roy. Belg., Ser. 2, Vol. L., pp. 18 and 21) are included by 

 Mr. R. Lydekker (Quart. Journ. Geol. Soc., Vol. XLIIL, p. 12, 

 1887, and Cat. Foss. Mam. Brit. Mus., Part v, p. 42, 1887) in 

 Brandt's Cetotherium. The tympanic bone of this genus is said 

 by Mr. Lydekker to be " distinguished from that of Balcenoptera 

 by its anteriorly pointed form, the triangular shape of the 

 roughened inferior surface, and the less flattened involucrum." 



To Cetotherium Brialmonti Mr. Lydekker refers an imperfect 

 axis vertebra in the British Museum (No. 46,734) from the Ked 

 Crag of Suffolk. The species was originally described from speci- 

 mens from the Antwerp Crag by Prof. Van Beneden (loc. cit. 

 and Ann. Mus. Roy. Hist. Nat. Belg.. Vol. IX., Part 4., p. 12, 

 1S85). 



CETOTIIERIUM (PLESIOCETUS) DUBIUM, v. BENEDEN. 

 PLATE VI,, FIGS. 10, b. 



This species, which is said to be smaller than C. Brialmonti, 

 was described by Prof. Van Beneden (Bull. Ac. Roy. Belg., Ser. 2, 

 Vol. XXXIV., p. 18, 1872, Vol. L., p. 18, 1880, and Ann. Mus. 

 Roy. Hist. Nat. Belg. Vol. IX., Part 4, p. 21, 1885) from speci- 

 mens found in the Antwerp Crag, and Mr. Lydekker (Quart. 

 Journ. Geol. Soc., Vol. XLIIL, p. 12, 1887) refers to the same 

 species two tympanics in the Museum of the Royal College of 

 Surgeons (Nos. 2,852, A. and B.) from the Nodule-bed of the 

 Red Crag of Suffolk and probably others in the British Museum 

 and Museum of Practical Geology from the same horizon. 



