832 Transactions. — Zoology. 



Witli the last-mentioned specimen I was able to compare the skull of a 

 young calf of Eubalcsna australis, the complete skeleton being in the College 

 of Surgeons Museum, London, and 12 feet in total length, the skull measur- 

 ing 36 inches, and the difference in the cranial characters of the two species 

 is found to be quite as obvious as in the more fully developed skulls. The 

 general outline of the two skulls at once distmguishes them. In Neobalcena 

 the greatest width is across the hinder border which is also concave in 

 outline, owing to the projection backwards and outwards of the exoccipitals 

 and squamosals, whereas in EubalcEua the greatest width is across the 

 orbital plates of the frontals, so that the posterior half of the skull is convex 

 in outline. 



In Neobalcena the skidl is less arched, the length being four times the 

 height of the arch between the glenoid processes and the tip of the beak, and 

 the supra-occipital is a narrow bone with a strong median ridge extending 

 forwards for half the total length of the skull ; but in the young Eubalcena 

 the height is equal to two-fifths the length, and the supra-occipital has a 

 circular outline, is flat, and extends over only one-fourth of the arch of the 

 skull. 



It is obvious that even at the earliest age these crania present marked 

 differences, while the divergence exhibited in the other osteological cha- 

 racters is still more striking. Thus comparing the complete skeleton of 

 Neobalcena, 14 feet 6 inches in length, with Eubalcena, we have — 



Neobalcena. Eubalcena. 

 Cervicals 7 7 



Dorsals . . . . . . 15 



Lumbars- . . . . . . 6 



Caudals (with chevrons) . . 6 

 ,, (without chevrons) 10 



15 

 12 



10 

 15 



44 59 



In Neobalcena the scapula is nearly twice as wide as high with strong 

 coracoid and acromion processes, almost as in BaUmioptera. In Eubalcena, 

 on the contrary, the scapula is high and narrow and with only one feeble 

 process. In the form of the vertebrae, sternal apparatus, and especially in 

 the quality and proportional dimensions of the baleen, Neobalcena has some 

 afiinity with the right- whale (Mijsticete) of the Arctic Seas, and it is not 

 unlikely that it may be a species abounding in the unexplored seas of far 

 southern latitudes, where it may attain to a large size, only stragglers 

 occasionally reaching to the latitude of New Zealand and Austraha. In these 

 seas the normal representative of the Balcenidcs is Eubalcena australis, just as 

 in the northern hemisphere Eubalcsna biscayensis in the temperate latitudes 

 of the Atlantic, and E. japonica, of the Pacific, replace the Mysticete of the 



