18/6.] DR. J. V. HAAST ON MESOPLOPON FLOWERI, 483 



is in the first three vertebrae a rounded apophysis ; in the next four 

 vertebrae it gradually enlarges, becoming, as in Epiodon novce-zea- 

 landice, laterally compressed, showing one strongly marked process 

 pointing upwards and forwards, as well as a well indicated and pos- 

 teriorly situated articulation for the tubercle of the ribs. A separa- 

 tion into two distinct processes takes place in the eighth, the forward 

 or anterior process of the apophysis now appearing as the metapo- 

 physis, and its lower or posterior process forming a lower transverse 

 process, starting as a small rounded prominence from the anterior 

 border of the upper portion of the body, and on which the articular 

 surface for the eighth rib is situated, directed obliquely backwards. 



In the ninth vertebra this separation is still more accomplished, 

 the metapophysis being well developed, and the transverse process, 

 which springs now from near the centre of the body, although thicker 

 and more rounded than those of the succeeding vertebrae, takes already 

 its usual form. It has an articular surface for the ninth rib on 

 its posterior end, with the same direction as in the preceding one. 



The tenth vertebra, which is the largest of the series, has a very 

 large transverse process, depressed and broad, on the edge of which 

 the tenth small rib obliquely articulates. This transverse process 

 is the broadest and longest of the whole series of vertebrae — those of 

 the lumbar region, beginning with the first, getting by degrees shorter 

 and narrower. 



The transverse process of the ninth thoracic vertebra has a hori- 

 zontal and somewhat backward direction ; that of the tenth stands 

 straight ; whilst the same process in the lumbar and in the first series 

 of the caudal vertebrae has, besides a slightly downward, also a for- 

 ward direction. The bodies of the thoracic vertebrae up to the 

 seventh have a flattened lower surface, after which a keel starts on 

 the eighth, which is well pronounced on the ninth and tenth. 



Lumbar Vertebra. 



The ten lumbar vertebrae resemble each other very much in form. 

 Gradually they become more elongated, the first having an antero- 

 posterior length of 4*55 inches, and the eighth of 6*30 inches, after 

 which they shorten again a little. They possess each a median keel, 

 and are compressed in the centre below the transverse process. The 

 spinous processes are large and high, increasing to the eighth, which 

 is 1 1 '50 inches high, after which they slightly decrease. The arches 

 arise from the centre of the bodies, thus differing from Berardius 

 and Epiodon, where they have a more anterior position. 



Caudal Vertebrae. 

 There are nineteen caudal vertebrae, of which the first ten have a 

 deep channel running along their lower surface. The spinous pro- 

 cesses gradually lose in height, that of the tenth vertebra consisting 

 only of a slight excrescence. The lower transverse processes also 

 shorten by degrees, so that in the sixth they are represented by a 

 small horizontal ridge, which is only faintly indicated in the seventh. 

 In the eighth, ninth, and tenth vertebrae all signs of such processes 



