RIGHT lVIfALS ny 



books of zoology. In his "Supplement," however, 

 Gray laid still greater emphasis upon the structural 

 divergences to be seen amono- the whalebone whales, 



o o 



and arranged them thus: Sub-order I., Balaenoidea, con- 



O 



taining but a single family Balsenidae ; and Sub-order 

 II., Balaenopteroidea, containing the families Agaphe- 

 lidae, Megapteridae, Physalidae, and Baleenopteridae. 

 The other extreme is accepted by most writers, who 



FIG. 20. Skull of Balanoptera sibbaldii, dorsal view. 

 (From van Beneden and Gervais.) 



SO, Supra occipital. P, Parietal. F, Frontal. N, Nasal. 



allow but a single family Balaenidae. I am disposed to 

 allow the two families Balsenidae and Balsenopteridae ; 

 but there is something to be said for but a single 

 family, chiefly on account of the characters of 

 Rhachianectes and Neobalcena. It is rather curious that 

 Dr. Gray with his liberality in the manufacture of 

 families did not dignify the last named by creating 

 a special family for it. Especially as he divided the 

 Rorquals into two families. 



