1867.] DR. H. BURMEISTER ON PONTOPORIA BLAINVILLII. 48.5 



only 3 lines long, and the last 10 lines. The spinous processes are 

 not very high, but tolerably broad ; the anterior one much inclined; 

 the posterior directed more perpendicularly, and double the breadth 

 of the former. The transverse processes decrease in length from the 

 first to the seventh, but increase in breadth ; and from there to the 

 tenth they become again longer, as well as broader, the tenth being 

 16 lines long, and the seventh only 7 lines. Each of these processes 

 has a projection on the anterior margin near the base, and an oblique 

 truncated tip, to which the rib is articulated. 



The seven lumbar vertebrae are the largest and strongest of all, 

 the first being 1 1 lines long and the seventh 12 lines. All have high 

 and large spinous processes, which become somewhat higher poste- 

 riorly, so that the three last lumbar vertebrae are the highest of all. 

 The transverse processes of these same vertebrae are extremely broad, 

 and not directed forwards as in the typical Dolphins, but rather 

 backwards : near the base on the fore and hinder margin of each pro- 

 cess is a prominent tubercle, which is stronger on the fore margin 

 than on the hinder ; and by these projections the processes are 

 united to each other. Even on the fourth, fifth, and sixth lumbar 

 vertebrae the tubercles overlap each other, the hinder of the anterior 

 vertebra lying upon the fore ones of the posterior (see fig. 1), and 



Fig. 1. 



Ponfoporia Main villii. 



The second and third lumbar vertebrae, natural size, seen from below. 



a a. Second vertebra, b h. Third vertebra. 



forming in this manner a sort of secondary articulation between the 

 vertebrae, which must make the movement of the lumbar portion of 

 the body very strong, and the vertebral column, if contracted, very 

 firm. 



The eighteen caudal vertebrae are of very different form and 

 size, and have together a length of 9 inches 8 lines. The first five 

 have inferior spinous processes, and the same, with the sixth, also 

 superior spines ; but each one is somewhat smaller and lower than 

 the foregoing. The transverse processes are much shorter than in 

 the lumbar portion, and do not touch each other with their tubero- 

 sities ; they soon become smaller, and lose their prominent tip. This 

 decrease is so rapid, that already the fifth caudal vertebra has no 



