294 LILLJEBORG ON THE 



3rd Gemis — Balæna, Linné. 

 {Leiobalana, Escliricht.) 



Lower side of body without longitudinal furrows, and the back without fin. Whales of 

 this genus are, like those of the preceding, of a thick and robust form of body. The head is large 

 and blunt, and the mouth strongly arched. Body tapering greatly towards the tail. The caudal 

 fin very large, and deeply notched in the middle of the posterior edge. 



The skull differs very much from that of the preceding genus ; the nose is longer, con- 

 siderably narrower, and strongly arched. The intermaxillary bones are, when seen from above, 

 wider than the superior maxillaries, and partly cover them. The processus zygomatici of 

 the superior maxillaries and the orbital parts of the frontal bones are comparatively longer and 

 narrower. The superior maxillary bones are wide on the palate side, and have there, in their 

 posterior edge, outside of the palate bones, a deep and narrow notch, which is not found in the 

 preceding. The lower jawbones are more dr less strongly curved, and have no distinct processus 

 coronoideus, although their upper edge sometimes projects considerably.^ The facial region being 

 nan-ower than in the BaJcenopte.ræ, the distance from the middle of the lower jawbones to the 

 upper jawbones is consequently larger than in those ; and as this space is occupied by the 

 baleen, the blades are longer in all the species of the genus Balæna than in the preceding genera ; 

 and they are, in certain species, for instance the Greenland whale, in which the beak is very long 

 and arched, and the lower jawbones very much curved, much longer, indeed several times 

 longer, than the baleen of the preceding. The fibres in which they end, at the point and on the 

 inner edge, are finer, and the baleen is not twisted, as in them. The vertebræ are, like those of 

 the genus Megaptera, generally shorter and wider than in the Balænopteræ ; but their processes 

 are strongly developed, particularly the lateral processes of the lumbosacral vertebræ. The pro- 

 cessus obliqui of the posterior lumbosacral vertebræ, and of the caudal vertebræ, are further 

 separate than in the preceding genera. The cervical vertebræ are less developed, and at least 

 the greater part of them are firmly ankylosed. The sternum is of a simple form, and seems to 

 be subject to variations, even in the same species. The ribs are generally thick and large, and 

 some of them have a conspicuous tuberculum, collum, and capitulum, and seem to be articulated 

 to the corpora vertebrarum. The scapula is large, but not so broad as in the preceding genus ; 

 the breadth does not much exceed the length. It has always an acromion, but is most often 

 without a processus coracoideus. The os humeri is short and with a large caput, strongly 

 directed inwards, almost to the side of the upper end of the bone, and is, consequently, not 

 terminal. The lower arm-bones are very large and broad, and comparatively shorter than those 

 of the preceding genera. The fingers are 5, and the hand broad. 



Species of this genus inhabit all seas. J. E. Gray (' Zoology of the Erebus and Terror') 

 mentions 5 species, and besides these one doubtful ; viz., Balæna mysticetus, Linné, from the 

 northern polar sea; B. australis, Desmoulin, from the sea at the Cape of Good Hope and the 

 Southern Sea, B. jajjonica, Gray, from the sea at Japan ; and B. antarctica and marginata 



^ See, for instance, G. Cuvier's figure of the skull of the young of Balæna australis. 



