30 



W. LlLLJEBORG, 



we may approximate vely estimate tlie entire length of the skeleton at about 

 45—50 feet. 



In proportion to the length of the skeleton the ribs are thick and 

 large, the length of the longest being about ~ of the skeletons. This pro- 

 portion shows that the form of the body was slender and elongated, most 

 like that of the Physalus musculus, in which the longest rib is a trifle less 

 than -§• of the skeletons length, i. e. in the case of an old male (Bergens 

 museum); slenderer than that of the Balaenoptera rostrata, where that length 

 in a younger specimen is about midway betwen j- and jr of the skeletons, 

 and in a still greater degree slenderer than that of the Megaptera hoops, 

 where the same length is about \ of the skeletons. Its bone-framework is 

 however stout and strong, on which account we have given it the specialname 

 robusta. In form the ribs in general agree most with those of the Physalus 

 muscidus, but are comparatively something stouter and broader, and in that 

 respect exhibit a tendency towards the form they have in the Balaena, to 

 which genus they approximate also in the circumstance of the two pairs 

 having a more strongly developed collum than any other Balaenopterid, 

 and were possibly fastened by their capitula to the corpora vertebrarum. All 

 have the lower end tapering, but more or less thin and compressed, and 

 those that are foremost are pretty broad just above the tapering point, with 

 tolerably sharp edges. From the number of them that have been found, as 

 well as from the ordinary normal continuous change, which they show 

 among themselves, we may with the greatest probability infer, that their 

 number was 15 pairs, of which the first pair only is totally wanting. In all 

 Whalebone Whales the first pair is broadest at the lower end, and as the 

 first pair of the discovered ribs of this whale has the lower end tapering, 

 Ave are compelled to assume that these not are the first pair in the skeleton. 

 As these ribs are very similar to the 2 nd pair of the Physalus musculns, we 

 consider that Ave are justified in assuming them to be that pair. 



The 2 nd pair of ribs (PI. VI. figg. 47, 48) are distinguished from 

 the following by greater breadth in proportion to their length, that breadth 

 being especially remarkable a little above the lower end. At that end they 

 are very thin with both edges sharp. They are not distinguished by any 

 particularly strong curvature at the upper end, but they have there a "ca- 

 pitular process" longer and sharper on the left rib (fig. 47) than on the 

 right (fig. 48). 



Of the 3 rd pair of ribs only the lower portion of the left is found 

 (PI. VI. fig. 49). This fragment in respect to form stands between the 

 2 nd and 4 ttl pairs, as being somewhat narrower than the second pair, 



