60 MAMMALIA. 



BAL^NA (BAL^SNULA) BAL^ENOPSIS, v. BENEDEN. 

 PLATE VI., FIGS. 5, b. 



The tympanic bones of this species are said to be very similar 

 to those of the last, but snriller. Balcena balcvnopsis was described 

 by Prof. Van Beneden (Bull. Acad. Roy. Belg., Ser. 2, Vol. 

 XXXIV., p. 11, 1872, and Ann. Mus. Hoy. Hist. Nat. Belg., Vol. 

 IV., Part 2, p. 52, 1880), from specimens found in the Antwerp 

 Crag, and Mr. Lydekker (Quart. Journ. Geol. Soc., Vol. XLIII., 

 p. 10, 1887) has identified tympanics of the same form in the 

 British Museum form the Nodule-bed of the Red Crag of Suffolk, 

 while an atlas vertebra from the true Coralline Crag of Sudbourn, 

 Suffolk, also in the British Museum (No. M. 3,542), has been 

 referred to this species by Prof. Van Beneden. 



Genus MEGAPTERA, Gray. 

 MEGAPTERA APFINIS, v. BENEDEN. 

 PLATE VI., FIGS. 6, b. 



The bones from the Antwerp Crag named M. affinis by Prof. 

 Van Beneden (Bull. Ac. Roy. Belg., Ser. 2, Vol. L., p. 13, 1880, 

 and Ann. Mus. Roy. Hist. Nat. Belg., Vol. VII., Part, 3, 

 p. 39, 1882), were previously called by the same writer Megapteropsis 

 robusta (Bull. Ac. R. Belg., Ser. 2, Vol. XXXIV., p. 15, 1872). 



Mr. Lydekker (Quart. Journ. Geol. Soc., Vol. XLIIL, p. 11, 

 1887) provisionally refers to this species a right tympanic from 

 the true Coralline Crag of Sudbourn, preserved in the Museum 

 of Practical Geology, which is characterised by its inflated form, 

 pear-shaped involucrum, and blunted anterior extremity. 



Another specimen in the Museum of Practical Geology from 

 the Nodule-bed of the Red Crag, near Ipswich, is also referred to 

 this species. 



MEGAPTERA (BURTINOPSIS) SIMILTS, v. BENEDEN. 



The genus Burtinopsis of Prof. Van Beneden (Bull. Ac. Roy. 

 Belg., Ser. 2, Vol. XXXIV., p. 19, 1872; also Vol. L., p. 16, 

 1880, and Ann. Mus. Roy. Hist. Nat. Belg., Vol. VII., Part 3, 

 p. 77, 1882) is disallowed by Mr. Lydekker (Quart. Journ. GeoJ. 

 Soc., Vol. XLIIL, p. 11, 1887), who includes the forms so named 

 under the genus Megaptera and with some doubt refers to the 

 species M. similis a left periotic from the Nodule-bed of the Red 

 Crag of Woodbridge, in the British Museum (No. 39,020) ; and it 

 appears from his remarks that the three forms of Megaptera- tym- 

 panics which he has found in the English Crags are distinguished 

 chiefly by their difference of size, the forms being nearly identical. 

 The Antwerp Crag and the Nodule-bed of the Red Crag of Suffolk 

 are the only places from which this species has been obtained. 



