81 
I have preserved the objects in alcohol, and prepared them myself 
with knife and pincette, by which operation the bones remained 
connected by natural ligaments. The preparations are placed in alco- 
hol and a number of the drawings have been copied at an enlarge- 
ment of */, *). 
If one can agree to the view that transformation-processes take 
place in the vertebral column, the examined 100 vertebral columns 
can be divided, on account of certain peculiarities of these proces- 
ses, into two groups. 
One group contains 80 specimens, the other 20. These figures 
indicate already, that the first mentioned group is the more import- 
ant one. This be therefore discussed first. 
Not one of the 80 vertebral columns is perfectly identical with 
another. 
Most points of difference are little deviations in form, which how- 
ever morphologically are not without signification. If one leaves these 
aside, and pays only attention to differences that are so great, that 
they can influence the formula of the vertebral column, one sees, 
that in the group of 80 vertebral columns ten dijjerent forms are 
represented, which can be indicated by formulas. These are the 
formulas Zf to //a and //e to 1115 of the subjoined list; vide 
page 82. 
As an explanation of these formulas it be pointed out, that the 
vertebrae are indicated by figures, denoting their place in the column. 
The counting starts from the atlas as the first vertebra. 
The vertebrae in different vertebral columns that are indicated 
by the same figure, are morphologically equivalent, because it has 
appeared, that in case of transformations of vertebral columns no 
vertebra falls out of the series, or is newly formed in the series 
between vertebrae, that exist already. 
According to their form the vertebrae are taken in groups — the 
regions of the vertebral column — and the vertebrae in each region 
are indicated by letters corresponding with the names of the regions. 
The vertebrae of the cervical region are indicated by cv. In the 
normal vertebral column this region contains the first vertebra up 
to the 7® included. 
The vertebrae of the dorsal region are indicated by d. There are 
12, consequently the 8" up to the 19'" included. They are charac- 
terized by the fact, that each vertebra is provided with one pair of 
ribs movably united to it. 
1) These drawings were demonstrated at the meeting; they will be published 
on another occasion. 
6 
Proceedings Royal Acad. Amsterdam, Vol. XV. 
