OSTEOLOGY OF THE PIGMY WHALE. 107 



(5) The proportions of the arm to the forearm. 



(6) The existence of only four fingers in the manus ^. 



(7) The presence of a dorsal fin. 



The anatomical features in which Neohalwna is peculiar and disagrees with both 

 Right Whales and Eorquals are more numerous still ; they are as follows : — 



(1) Small size {cf., however, Baloenoptera rostrata). 



(2) The great length of the region of the skull which lies behind the orbit. 



(3) The depth and the form generally of the mandibles. 



(4) The large quadrangular lower transverse processes of the cervical vertebrae. 



(5) The great shortness of the entire vertebral column. 



(6) The extremely reduced lumbar region of the vertebral column. 



(7) The large number of the ribs, their breadth and flatness, and the commence- 



ment of the series with the second and not the first dorsal vertebra. 



(8) The shape of the sternum. 



From these facts a definition of the genus may be compiled, and will be the 

 following : — 



Genus Neobal^-ena. — Size small, 20 feet or so. Dorsal fin present. Xo throat- 

 grooves. Head hardly more than one-fifth of the length of the entire body. Baleen 

 long. Skull like that of Balcena, but with much produced postorbital region and 

 broader frontals. Mandible deep, with only a rudimentary coronoid process. Cervical 

 vertebrae completely fused, the lower transverse processes forming a strong quad- 

 rangular mass. Dorsals 18 in number. Lumbars 2. Caudals 16. Ribs very numerous, 

 17 pairs, the first attached to the second dorsal vertebra ; the posterior ribs broad and 

 flattened, the first six only with traces of capitulum. Shoulder-girdle elongated 

 antero-posterioiiy, with long coracoid and acromion. Head shorter than radius. 

 Digits four. Sternum cross-shaped. 



P.S., May 1901. — Since this paper was read, Mr. S. F. Harmer, F.R.S., has kindly 

 directed my attention to a skeleton of Neohalcena marginata in the Museum at 

 Cambridge. In this example, which is immature, the epiphyses of the vertebrae being 

 quite separable, the sternum has an outline different from both the two examples with 

 which 1 have dealt above. In the Cambridge specimen the outline is roughly that of a 

 half an oval divided across the longer diameter. The straight edge forms the anterior 

 border. 



There are seventeen ribs on each side, and to the first dorsal vertebra no rib is 



^ 1 am, of course, aware that Dr. Kiikenthal (" Die Walthiere," in Denksehr. Jen. Ges. 1889) has shown that 

 in Balcenoptera musGulus there are a series of cartilaginous pieces intercalated between the third and fourth 

 fingers, which he considers to represent the missing digit of the adult Rorqual hand. If this be shown to be 

 a general feature, it will not interfere with the anatomical difference between Balcena and Balamopiera in the 

 manus, though it will, of course, show that the supposed thumb is not the equivalent of that digit. 



