304 LILLJEBORG ON THE 



the same thickness from one end to the other. Their sides arc even, with the outer edge slightly 

 convex, while the inner edge is concave. The fibres on its inner edge are very fine and of a 

 black colour. The internal fibrous layer, of which these fibres form a continuation, occupies only 

 a small part of the substance of the blades, and is of a fine uniform texture. The harder and 

 closer layer, which covers the fibrous one and forms the greater part of the substance, is generally 

 blackish, and is externally covered by a polished grey or greyish-black enamel (J. E. Gray). They 

 decrease in length towards the anterior as well as the posterior part of the upper jaw, and both 

 the hinder and the fore ones are very short. They are less wide at the base than those of the 

 Balænopteræ, the greatest width being 10" — 12", a natural consequence of the upper jaw-bones 

 being narrower than in the latter, but they are thicker.^ Scoresby counted more than 300 

 transverse series of whalebones on each side. The colour is above, on the greater part of the 

 lower jaw, and on the pectoral fins and the caudal fin, black. The front part of the lower jaw, 

 sometimes a small part of the point of the upper jaw and a part of the belly, are white. The 

 eyehds, the tail before the caudal fin, and the axillæ, are grey. The older specimens have 

 sometimes white spots. 



The skeleton is chiefly remarkable for the length of the head and ribs, for the long lateral 



processes of the lumbosacral vertebrae, for the vertebrae generally being short, for the size of 



the scapula and humerus, and for the large, but short and wide, lower arm-bones. The head is 



of a comparatively slender structure, although each bone by itself seems large and massive 



in consequence of its colossal dimensions. The skull is remarkable for the beak or facial 



region being elongated, narrow, and strongly arched, and about three times as long as the 



hinder part of the skull. Moreover, the posterior part of the skull is not wide in consequence of 



the narrow processus zygomatici of the superior maxillaries and the orbital parts of the frontal 



bones being directed strongly backwards. The posterior margin of the occipital bone has a rather 



deep concavity, so that the lateral parts of the occipital bone as well as the temporal bone extend 



further back than the articulating condyles of the occipital bone. The temporal bones are dilated 



at their outer end, both backwards at the processus articularis and forward at the processus 



zygomatici, and are there almost irregularly square. Each frontal bone forms a projecting point 



above the nasal bone. The intermaxillary bones from above do not seem much wider than the 



superior maxillaries. The palate bones on the lower side of the skull are short and do not 



extend as far as the base of the nose. The cleft in the hinder edge of the superior maxillaries 



is very narrow and deep.^ The lower jaw-bones are large, but are of such an immense length 



that they do not seem thick when compared with those of the Balænopteræ. They are strongly 



curved, and a slightly elevated ridge is the only indication of a processus coronoideus. The lower 



margin is somewhat convex, particularly in front of the angulus. Its greatest height is above 



the condylus. The lower jaw-bones were about 22' long along the curve on the outer side, and 



2' 4" high at the condylus on the first-named skeleton in Copenhagen, which seems to have been 



about 50' long. One of a pair of lower jaw-bones, that for a long time have been preserved in 



the hall of the Royal Scientific Society here, is I85' long along the curve, and 21" high at the 



place where the processus coronoideus is indicated, and 11" at the middle. I counted 54 vertebrae 



^ The whalebone of the Greenland whale is considered to be the best, as being more even, 

 longer, and of a finer structure. 



^ These characters of the skull are from G. Cuvier. 



