xtreme length is to the extreme breadth as 100 to not more
than 67, and the transverse diameter of the human skull may fall below
even this proportion. People having such skulls were called by Retzius
'dolichocephalic.'

The most cursory glance at the side views of these two skulls will
suffice to prove that they differ, in another respect, to a very
striking extent. The profile of the face of the Calmuck is almost
vertical, the facial bones being thrown downwards and under the forepart
of the skull. The profile of the face of the Negro, on the other hand,
is singularly inclined, the front part of the jaws projecting far
forward beyond the level of the fore part of the skull. In the former
case the skull is said to be 'orthognathous' or straight-jawed; in the
latter, it is called 'prognathous,' a term which has been rendered, with
more force than elegance, by the Saxon equivalent,--'snouty.'

Various methods have been devised in order to express with some accuracy
the degree of prognathism or orthognathism of any given skull; most of
these methods being essentially modifications of that devised by Peter
Camper, in order to attain what he called the 'facial angle.'

But a little consideration will show that any 'facial angle' that has
been devised, can be competent to express the structural modifications
involved in prognathism and orthognathism, only in a rough and general
sort of way. For the lines, the intersection of which forms the facial
angle, are drawn through points of the skull, the position of each
of which is modified by a number of circumstances, so that the angle
obtained is a complex resultant of all these circumstances, and is not
the expression of any one definite organic relation of the parts of the
skull.

(FIGURE 26.--Side and front views of the round and orthognathous skull
of a Calmuck, after Von Baer. One-third the natural size.)

I have arrived at the conviction that no comparison of crania is worth
very much, that is not founded upon the establishment of a relatively
fixed base line, to which the measurements, in all cases, must be
referred. Nor do I think it is a very difficult matter to decide what
that base line should be. The parts of the skull, like those of the rest
of the animal framework, are developed in succession the base of
the skull is formed before its sides and roof; it is converted into
cartilage earlier and more completely than the sides and roof: and the
cartilaginous base