36 CETACEA. 



as well as with another specimen in the Museum of the 

 Royal College of Surgeons (No. 2805). It differs from the 

 tympanic of D. yoropi (No. M. 3517, below) by its some- 

 what superior size, greater relative width, greater height 

 of the inner wall, smaller depth of the eustachian notch, 

 sharper posterior angle, and more gibbous involucrum. 



Made in the Museum, 1886. 



Balsenoptera goropi (Yan Beneden : ). 



Syn. Plesiocetus goropi, Van Beneden 2 . 



Balcenoptera musculoides, Van Beneden 3 . 



This species is closely allied in size and structure to B. musculus, 

 of which it may be the ancestor. The existing species attains a 

 length of at least 70 feet ; and the fossil one is very common in the 

 Antwerp Crag. 



Hob. Europe (Belgium and England). 



M. 3517. The imperfect left tympanic ; from the Antwerp Crag. 



This specimen is indistinguishable from the one figured 



by Van Beneden in the Ann. Mus. 11. Hist. Nat. Belg.' 



vol. vii. pt. 3, pi. liv. fig. 18. By exchange -with the lioyal 



Brussels Museum of Natural History, 1886. 



M. 3517 a. A precisely similar left tympanic ; from the Antwerp 



Crag. By exchange with the Royal Brussels Museum 



of Natural History, 1886. 



39016. A much-rolled right tympanic, agreeing very closely with 

 the preceding specimens ; from the lied Crag of Wood- 

 bridge, Suffolk. Noticed by the present writer in the 

 4 Quart. Journ. Geol. Soc.' vol. xliii. p. 12. 



Purchased, 1865. 



The folloiving specimens from the Antwerp Crag are provisionally 

 referred to this species, although some of them may belong to 

 Cetotherium brialmonti. 



43601. The centrum and part of the neural arch of the first dorsal 



1 Bull. Ac. E. Belg. ser. 2, vol. xxxiv. p. 15 (1872). Cetotherium ; the specific 

 name is misprinted garopi. 



a Loc. cit. 



* Ibid. vol. 1. p. 15 (1880). When the generic name was changed the founder 

 also proposed a new specific one ; but there is no justification for the substi- 

 tution. 



