47 



M. 3567. The centrum and left transverse process of a dorsal 

 vertebra, not improbably belonging to this species ; from 

 the Antwerp Crag. Purchased. 



Cetotherium affine (Van Beneden '). 

 Syn. Hcterocetus affinis, Van Beneden 2 . 



This species is rather smaller than the preceding, and has shorter 

 frontals and a lower cranium. 

 Hob. Europe (Belgium). 



M. 3530. The nearly perfect right tympanic of a young individual, 

 agreeing with the specimens in the Brussels Museum which 

 are referred to this species ; from the Antwerp Crag. 



By exchange with the Royal Brussels 

 Museum of Natural History, 1886. 



Genus HERPETOCETUS, Van Beneden 3 . 



This genus is characterized by the remarkably inflated and egg- 

 like tympanic (in which the involucrum has a very peculiar shape), 

 and by the presence of a long talon to the mandibular condyle ; the 

 latter feature indicating affinity with the Pliyseteridce. The tym- 

 panic is more like that of Megaptera than that of Cetotherium, but 

 is distinguished by the abrupt outer border of the involucrum, and 

 the filling-up of a great part of the cavity by bone. 



Herpetocetus scaldiensis, Van Beneden 4 . 

 This is the typical and only species, and is of comparatively small 

 size. 



Hob. Europe (Belgium and England). 



M. 3534. The imperfect right tympanic ; from the Antwerp Crag. 

 This specimen agrees exactly with the type examples 

 figured by Van Beneden in the ' Ann. Mus. R. Hist. Nat. 

 Belg.' vol. vii. pt. 3, pi. cv. 



By exchange with the Royal Brussels 

 Museum of Natural History, 1886. 



1 Bull. Ac. E. Belg. ser. 2, vol. 1. p. 21 (1880). Heterocetus. 



2 Loc. cit. 



3 Ibid. vol. xxxiv. p. 20 (1872). Amended from Erpctocetus. 



4 Loc. cit. 



