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. Heierocetus affinis, Van Beneden ^. 



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

 frontals and a lower cranium. 

 Hah. Earope (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 exclicmge luitli the Royal Brussels 

 Museum of Natural History, 1886. 



Genus HERPETOCETUS, Tan Beneden \ 



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 afiinit}' with the Fhyseteridce. The tym- 

 panic is more like that of Mcgaptera 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, Yan Beneden ^. 



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

 size. 



Hah. Europe (Belgium and England). 



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

 This specimen agrees exactly with the type examples 

 figured by Yan Beneden in the ' Ann. Mus. E. Hist. Xat. 

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



By exchange ivith the Royal Brussels 

 Museum of Natural History, 1886. 



' BuU. Ac. E. Belg. ser. 2, vol. 1. p. 21 {lSSO).—Hcterocefus. 

 2 Loc. cit. 



^ Ibid. vol. xxxiv. p. 20 (1872). — Amended from Erpdocctiis. 

 ^ Loc. cit. 



