SEALS AND WHALES OF THE BRITLSH SEAS. 47 



chief organ of locomotion : it is always fixed horizontally, and is of great 

 size and power, enabling the animal, by its vigorous use, to attain great 

 speed. There are many and striking peculiarities in the bony skeleton which 

 it is not necessary here to enumerate. 



Before proceeding to give some account of the species which have been 

 found in the British Seas, it will first be necessary to say a few words as to 

 the arrangement of the genera and species. I shall enter into this part of the 

 subject, however, so far only as is necessary for us clearly to understand the 

 relative positions of the species which we shall have to consider. 



Professor Flower divides the order Cetacea into two sub-orders : First, 

 Mystacocetiy or Balcsnoidea, in all the members of which baleen takes the place 

 of teeth, which are never developed, disappearing before birth ; second, 

 Odontoceti or Delphhioidea, in which teeth (sometimes very numerous) are 

 always developed after birth. The first sub-order is a very restricted one, 

 embracing only two families, BalcEuidcB and Balcznopteridcs, to the former of 

 which belong the two genera of Right- Whales, Balcena and EuhalcEua ; and 

 to the latter, two genera, namely, Megaptera and Bal<2noptcra. To these 

 two genera* belong the Rorquals, which occasionally occur in the British 

 seas. The second sub-order, OdoJitoceti, contains the families of Physeteridce, 

 represented by the Sperm Whale, Beaked Whale, and several allied species ; 

 PlatanistidcB, consisting of some curious forms found only in India and South 

 America ; and Delphinidce, comprising the Narwhal, Beluga, or White Whale, 

 Grampus, Porpoise, and Dolphins. The total number of British Cetacea 

 has been variously estimated; Dr. Gray, in 1864, described thirty, and in 

 1873 thirty-three species; while Bell, whom we shall follow, recognised only 

 twenty-two species in his second edition, published in 1874. 



The following table of the British Cetacea will serve to indicate at a 

 glance the precise position assigned to each species, in the two main divisions 

 into which the order is divided : — 



* Pkysalm, Benedenia, and Sibbaldius, of Gray, are now rejected, I believe, by Prof. Flower. 



