52 
MAURICE G. MEHL 
foramen is indicated by following the dotted circles near the 
distal end of this bone. These foramina may be further em- 
phasized by placing a cross within the circle. A hyperphalan- 
geate or hyperdactylate condition in the hand or foot may be 
indicated either by the addition of new squares or the splitting 
of the present rectangles by vertical or horizontal lines or both. 
The accompanying diagram, figure 1, shows how the com- 
pleted chart for a purely hypothetical form might appear. The 
features indicated are the loss of the shaft portion of the fibula 
and the fusion of the upper and lower ends of this bone with the 
tibia; the loss of the first, second, and fifth metatarsals and the 
partial fusion of the third and fourth; and the loss of all the 
phalanges in the first, second, and fifth fingers and the loss of 
one and two phalanges in the third and fourth fingers respec- 
tively. In the tarsus there are but two rows of bones with three 
elements in the proximal and two in the distal row. 
THE VERTEBRAE 
While the guide chart for the composition and modification 
of the vertebrae, plate XI, is not all that could be desired for 
certain primitive forms, it works well for the great majority of 
types. The names of the parts should be added by the student. 
In the end view given in this chart a perforate or solid centrum 
may be shown. The upper set of dotted angles near the neural 
canal is used to show the presence of the zygosphene and the 
lower set is for the hyposphene. While the lateral view shows 
the presence or absence of the hypocentrum and its relative size, 
it is also shown in the end view where it may be designated as a 
single unit or composed of two parts. 
In the lateral view the composition and modification of the 
centrum may be more fully shown. Temnospondylous types 
as illustrated by Cricotus and Eryops may be shown by util- 
izing certain of the dotted lines while holospondylous forms are 
indicated by ignoring these. The presence of an intercentrum 
is indicated by following another dotted line that cuts off a 
small triangular space in the lower anterior corner of the out- 
