OSTEOLOGY OF THE PIGMY WHALE. 99 



and third have capitular processes which reach nearly to the bodies of the vertebrae, 

 that of the second is rather the longest .... The neck becomes rudimentary in the 

 fourth and obsolete in the fifth and all succeeding ribs." In " Physalus latirostris " 

 (which appears to be identical with what is now known as Balwnojitera sihbcdcli) 

 there are fifteen pairs of ribs. But though there is one pair more than in the last 

 species the ribs are less modified. The second and third, according to Flower, have 

 well-developed capitular processes ; but these processes become " nearly obsolete " on 

 the fourth. 



The small Balmioptera rostrata has, in correspondence with its diminished size, 

 fewer ribs than its gigantic allies. It has only eleven pairs of these bones. MM. van 

 Beneden and Gervais find from an examination of skeletons that, as in other Rorquals, 

 the first pair are without a capitulum. It is not necessary to go into further details 

 concerning the characters of the ribs in the Whalebone Whales. I may say that the 

 facts given above have been verified by me in the skeletons of these whales in London. 

 The principal generalization to be drawn from these facts is that the genus 

 Bakenoptera has a more imperfect series of ribs than the genus Balcena. Fewer 

 ribs in the former have the two heads of the typical mammalian rib. Now in this 

 feature it is clear that Neohalcena comes nearer to Bakenoptera than to Balcena. It is, 

 in fact, somewhat intermediate between the two. We might presume that Neohalcena 

 ofifers a more primitive state of afliairs than either of the remaining families of Right 

 Whales from certain points of view. It is perfectly clear that the original condition 

 of ribs is shown (so far as concerns the Mammalia) in the Monotremata. In that 

 group the ribs retain their primitive intercentral position, arising only from the bodies 

 of the vertebrse, and having no connection with the transverse processes of the 

 vertebrae. It does not, however, follow from this that Bakenoptera and Megaptera 

 exhibit the least archaic conditions, because there are so few ribs which retain at any 

 rate traces of the presumably primitive connection of the ribs with the centra of their 

 vertebrae. It seems to me that Prof. Max Weber ^ has shown conclusively, in 

 opposition to Prof. Albrecht ", that we must look upon whales as definitely 

 " eutherian " mammalia and as not representing in any way the problematical 

 " promammalia." If that be so, the ribs of whales are derived from those of some 

 terrestrial mammal in which both central and tubercular heads were present. The 

 loss of the former and the feeble development of the latter are to be explained by 

 respiratory exigencies, necessitating an imperfect articulation with the vertebrse at 

 both points. 



This allows of course of a greater expansion of the chest-cavity and a consequent 

 completer filling of the lungs with air. If it could be shown that Neohalcena is a 



^ Weber, " Ueber die Cetoide Natur der Promammalia," Anat. Anz. ii. 

 - Albrecht, " Ueber die Cetoide Natur der Promammalia," ibid. i. p. 338. 



