418 ANATOMY OF VEHTEBRATES. 



In the common Porpoise {Phoc(Bna communis) all the cervicals 

 are anchylosed, and the head of the first free rib rests upon their 

 coalesced bodies : there are fifty-six other vertebrae, thirteen of 

 which are ' dorsal,' or have moveable ribs. The diapophyses and 

 spines of the lumbo-caudal vertebra incline forward. In the 

 Narwhal all the seven cervicals are free : the wielding of the 

 horn-like tusk of the male is the condition of their greater freedom 

 of movement in the neck. Beyond the cervicals are fifty-six 

 vertebrae, twelve of which have moveable ribs, and of these six pairs 

 join the sternum. In the Bident Dolphin, or Bottle-nosed Whale 

 {llijiieroodon hidens), the cervical vertebrae have coalesced with one 

 another: beyond these there are thirty-eight free vertebrae, of which 

 only the nine anterior bear moveable ribs: the twenty-second 

 vertebra first bears h^emapophyses attached to the under part of 

 the centrum. The five anterior pairs of ribs articulate witli the 

 sternum, which consists of three bones. 



In the Balcena mysticetus, fig. 159, there are thirteen dorsals; 

 as many vertebrae without ribs intervene between these and the 

 first vertebra with h^emapophyses ; the rest of the column, this 

 inclusive, consists of twenty-two vertebrae, the last dozen being 

 reduced to the centrum, which is much depressed, the last two or 

 three coalesce. The seven cervical, ib. c, are blended into one bone. 



In a young or fostal Whale {Balcena austi^dis) ^ the cervical 

 neurapophyses of one side are disunited above from those of the 

 other side, as they are from the centrum below : a compressed 

 diapophysis is sent off from the outer side of each ; it is shortest 

 and thickest in the atlas. The third and fourth neurapophyses 

 have coalesced at their upper part on the left side, and those of 

 the last five vertebrae have coalesced on the right side. The 

 cortical portion of the centrum of the atlas is ossified, and forms 

 a wedge-shaped piece of bone, like the corresponding part in the 

 Ichthyosaurus. The centrums of all the cervicals are connate. 

 In the adult true Whales {Balcena), the cervicals, fig. 283, 1-7, 

 are distinguishable mainly by the intervals for the passage of the 

 nerves between the neural arches. In Balcenoptera rostrata, anchy- 

 losis does not proceed farther than to unite the atlas with the 

 dentata, and the sixth with the seventh vertebra. In Bal. boops, 

 Bal. patachoniclia, and some other Fin- whales, the atlas retains its 

 individuality. The interval between the lower (pleurapophysial), 

 fig. 283, /?, and upper (diapophysial), ib. d, part of the transverse 

 process is wide, often open, and when circumscribed usually leaves 

 a large foramen. In the seventh cervical the diapophysis, d, alone 



' XLiv. vol. ii. p. 440, no. 2437. 



