416 CETACEA. 



fin also of Fseudorca is placed about the middle of the back, but in its height it 

 approaches more to the high dorsal of Orca than to the low dorsal of Olohicephalus. 

 Fseudorca also, in the fewer number of its vertebrge, 50, departs even more from this 

 form than does Orca, and in its lower spinous processes and in the union of its first 

 six cervical vertebrae, it differs considerably from this genus. The pectoral limb of 

 Fseudorca is narrow like the anterior extremity of GloUcephalus and Grampus, 

 but is proportionally very much shorter and smaller. It is, however, very different 

 from that of Orcella, which is situated further away from the head, and is consider- 

 ably broader and more powerful. The scapula of Orcella in its great length and in 

 the curvature of its glenoid and acromial borders approaches more to the scapula of 

 Fseudorca than to the scapula of either Orca or GloUcephalus, but it is distinct from 

 any of them. Its humerus, radius, and ulna are much longer than in Fseudorca, 

 and its manus is perfectly distinct from the narrow manus of the latter, in which the 

 fingers, especially the second and third, are close together, giving rise to a narrow 

 flipper, whereas in Orcella, they are along with the other fingers expanded and 

 widely apart, producing a moderately broad fin. In Orcella the phalanges are 

 broader than long, in Fseudorca longer than broad. The skuUs also of these two 

 forms differ as much from each other as they do from GloUcephalus and Grampus 

 respectively, and as do the two latter from each other ; indeed the skuU of Orcella, 

 taken in all its features, has a closer resemblance to the skuU of Grampus than to 

 the skull of Fseudorca. 



The skull is distinguished from that of GloUcephalus by its much less laterally 

 extended premaxillaries and its vertebral column, by the union of only two of its 

 cervical vertebrae, an event which probably takes place after uterine life by anchylosis 

 of two previously existing segments, whereas, in GloUcephalus, all the cervical 

 vertebrae are anchylosed or rather form one single bone as they originally formed 

 one single cartilage. I have also referred to other structural differences that exist 

 between the vertebral columns of GloUcephalus and Orcella, more especially to the 

 differences in proportion between the transverse and spinous processes. 



Prom such considerations as these, and viewing the structure of Orcella as a 

 whole contrasted with that of each of the already named genera, to each of which 

 it presents certain features of resemblance, associated, however, with marked dis- 

 similarities, it is evident that Orcella presents an assemblage of characters which 

 remove it from any of these genera and entitle it to generic rank. These charac- 

 ters may be expressed as follows : — 



Head globular ; dorsal fin low, situated behind the middle of the body ; pec- 

 toral fins oval, about one- sixth the length of the animal. Teeth conical, larger and 

 fewer in the lower than in the upper jaw ; 13 to 17 teeth in upper and 12 to 14 

 teeth in the lower jaw. Skull beaked ; beak broad at the base, anteriorly pointed ; 

 premaxillary not much laterally dilated, bearing one tooth ; vertebrae 62 to 63 ; first 

 two cervical vertebrae anchylosed. Lumbar transverse processes moderately long; 

 yertebral ribs 12 to 13, with one to two free ribs. Pelvic bones opposite 35th and 

 36th vertebrae. 



