2<> CETACEA. 



Some of the following specimens may belong to young individuals 

 ofB. insignis. 



46078. The centrum of the seventh (?) dorsal vertebra ; from the 

 lied Crag of Boyton. Although much smaller, this speci- 

 men closely resembles the seventh dorsal of B. insignis, 

 No. M. 1301. Purchased, 1875. 



46495. The centrum of an early dorsal vertebra ; from Woodbridge. 

 This specimen is very similar to the young fifth dorsal of 

 B. insignis, 'No. M. 1304. Purchased, 1875. 



45843. The centrum of a very similar dorsal vertebra ; from Wood- 

 bridge. Purchased, 1875. 



46744. The centrum of a late dorsal vertebra ; from Woodbridge. 

 This specimen agrees with No. M. 1280. Purchased, 1875. 



46743. An imperfect lumbar vertebra ; from Woodbridge. 



Purchased, 1875. 



48479. A middle caudal vertebra ; from Woodbridge. 



Presented ly C. Falconer, Esq., 1867. 



Balsena insignis (Van Beneden *). 

 Syn. Salcenotus insignis, Van Beneden 2 . 



This species is larger than B. balcenopsis. The seventh cervical 

 is always, and the atlas generally, free, while in young individuals 

 the axis is sometimes detached ; the anchylosis of the other cervicals 

 is less complete than in existing species, and the atlas and the sixth 

 and seventh cervicals are much thicker ; in all the cervicals distinct 

 epiphyses are developed. The inferior surface of the tympanic is 

 very wide, the antero-iuferior angle more or less distinctly marked, 

 and the flattening of the anterior surface extending nearly or quite to 

 this point. The whole bone is more inflated, its involucrum thicker, 

 aud its inferior surface wider than in B. ajfinis ; but it is not 

 always easy to be quite sure that specimens may not belong to young 

 individuals of that species. In many of the above-mentioned 

 features an approximation is presented to the Balajnopterine section 

 of the family. 



Hob. Europe (Belgium, Italy, and England). 



1 Bull. Ac. E. Belg. scr. 2, vol. xxxiv. p. 13 (l&T2}.lial<Enotus. 



2 Loc. clt. 



