20 CETACEA. 



The follow incj specimens are provisionally referred to this species. 



8116. A dorsal vertebra ; from silt at Lewes, Sussex. 



Mantell Collection. Purchased^ 1836. 



33463. The centrum of a dorsal vertebra ; dredged off the eastern 



coast. Layton Collection. Purchased^ 1858. 



39224. An early caudal vertebra ; dredged from the Thames at 

 "Wandsworth. Purchased, 1865. 



M. 3541. The centrum of a later caudal vertebra, wanting the 

 epiphyses ; probably dredged from the sea. No history. . 



33460. The centrum of a late caudal vertebra; dredged off the 

 eastern coast. Layton Collection. Purchased^ 1858. 



46282. The left humerus ; dredged from the JSTorth Sea. 



Oiules Collection. Purchased, 1874. 



Balsena primigenia, Van Beneden ^ 



This species is of large size and has all the cervical vertebrae 

 anchylosed together. The tympanies provisionally included under 

 this specific name present considerable variations, but, as they all 

 seem to pass into one another, these variations cannot apparently be 

 considered of specific value. Generally the tympanic is charac- 

 terized by the convex inferior border, the absence of a produced 

 antero-inferior angle, and the comparative lowness of the eustachian 

 portion of the aperture. This type of tympanic indicates a species 

 allied to the existing Whales of the southern and temperate seas 

 {B. hiscayensis and B. australis) ; but some specimens appear to 

 show a relationship to Neohcdcena. 



Hah. Europe (Belgium and England). 



Variety K. 



In this, which may be called the type variety, the inner wall of 

 the tympanic is very high, its superior border oblique, the flattening 

 of the anterior surface extending nearly or quite down to the inferior 

 border, the involucrum considerably thickened, and the inferior 

 border somewhat angulated. 



M. 1248. Cast of the right tympanic. The original was obtained 

 from the Antwerp Crag, and is preserved in the Brussels 



1 Bull. Ac. E.Bjlg. 66r. 2, vol. xxxiv. p. 9 (1872). 



