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skin of human beings may present the most extraordinary diversities in
colour and in texture。
So far as our present knowledge goes； the majority of the structural
varieties to which allusion is here made； are individual。 The ape…like
arrangement of certain muscles which is occasionally met with* in the
white races of mankind； is not known to be more common among Negroes or
Australians： nor because the brain of the Hottentot Venus was found to
be smoother； to have its convolutions more symmetrically disposed； and
to be； so far； more ape…like than that of ordinary Europeans； are we
justified in concluding a like condition of the brain to prevail
universally among the lower races of mankind； however probable that
conclusion may be。
＇footnote＇ *See an excellent Essay by Mr。 Church on the
Myology of the Orang； in the 'Natural History Review'； for
1861。
We are； in fact； sadly wanting in information respecting the disposition
of the soft and destructible organs of every Race of Mankind but our
own； and even of the skeleton； our Museums are lamentably deficient in
every part but the cranium。 Skulls enough there are； and since the
time when Blumenbach and Camper first called attention to the marked and
singular differences which they exhibit； skull collecting and skull
measuring has been a zealously pursued branch of Natural History； and
the results obtained have been arranged and classified by various
writers； among whom the late active and able Retzius must always be the
first named。
Human skulls have been found to differ from one another； not merely in
their absolute size and in the absolute capacity of the brain case； but
in the proportions which the diameters of the latter bear to one
another； in the relative size of the bones of the face （and more
particularly of the jaws and teeth） as compared with those of the
skull； in the degree to which the upper jaw （which is of course
followed by the lower） is thrown backwards and downwards under the
fore…part of the brain case； or forwards and upward in front of and
beyond it。 They differ further in the relations of the transverse
diameter of the face； taken through the cheek bones； to the transverse
diameter of the skull； in the more rounded or more gable…like form of
the roof of the skull； and in the degree to which the hinder part of
the skull is flattened or projects beyond the ridge； into and below
which； the muscles of the neck are inserted。
In some skulls the brain case may be said to be 'round；' the extreme
length not exceeding the extreme breadth by a greater proportion than
100 to 80； while the difference may be much less。* Men possessing such
skulls were termed by Retzius 'brachycephalic；' and the skull of a
Calmuck； of which a front and side view （reduced outline copies of which
are given in Figure 26） are depicted by Von Baer in his excellent；
〃Crania selecta；〃 affords a very admirable example of that kind of
skull。 Other skulls； such as that of a Negro copied in Fig。 27 from
Mr。 Busk's 'Crania typica；' have a very different； greatly elongated
form； and may be termed 'oblong。' In this skull the extreme 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。'
＇footnote＇ *In no normal human skull does the breadth of the
brain…case exceed its length。
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。
FIG。 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 ossifies； and becomes soldered into one piece long
before the roof。 I conceive then that the base of the skull may be
demonstrated developmentally to be its relatively fixed part； the roof
and sides being relatively moveable。
Fig。 27。Oblong and prognathous skull of a Negro； side and front views。
One…third of the natural size。
The same truth is exemplified by the study of the modifications which
the skull undergoes in ascending from the lower animals up to man。
FIG。 28。Longitudinal and vertical sections of the skulls of a Beaver
（'Castor Canadensis'）； a Lemur （'L。 Catia'）； and a Baboon
（'Cynocephalus Papio'）； 'a b'； the basicranial axis； 'b c'； the
occipital plane； 'i T'； the tentorial plane； 'a d'； the olfactory plane；
'f e'； the basifacial axis； 'c b a'； occipital angle； 'T i a'；
tentorial angle； 'd a b'； olfactory angle； 'e f b'； cranio…facial angle；
'g h'； extreme length of the cavity which lodges the cerebral
hemispheres or 'cerebral length。' The length of the basicranial axis
as to this length； or； in other words； the proportional length of the
line 'g h' to that of 'a b' taken as 100； in the three skulls； is as
follows：Beaver 70 to 100； Lemur 119 to 100； Baboon 144 to 100。 In an
adult male Gorilla the cerebral length is as 170 to the basicranial
axis taken as 100； in the Negro （Fig。 29） as 236 to 100。 In the
Constantinople skull （Fig。 29） as 266 to 100。 The cranial difference
between the highest Ape's skull and the lowest Man's is therefore very
strikingly brought out by these measurements。 In the diagram of the
Baboon's skull the dotted lines 'd1 d2'； etc。； give the angles of the
Lemur's and Beaver's skull； as laid down upon the basicranial axis of
the Baboon。 The line 'a b' has the same length in each diagram。
In such a mammal as a Beaver （Fig。 28）； a line （'a b'。） drawn through
the bones； termed basioccipital； basisphenoid； and presphenoid； is very
long in proportion to the extreme length of the cavity which contains
the cerebral hemispheres （'g h'。）。 The plane of the occipital foramen
（'b c'。） forms a slightly acute angle with this 'basicranial axis；'
while the plane of the tentorium （'i T'。） is inclined at rather more
than 90 degrees to the 'basicranial axis'； and so is the plane of the
perforated plate （'a d'。）； by which the filaments of the olfactory nerve
leave the skull。 Again； a line drawn through the axis of the face；
between the bones called ethmoid and vomerthe 〃basifacial axis〃 （'f
e'。） forms an exceedingly obtuse angle； where； when produced； it cuts
the 'basicranial axis。'
If the angle made by the line 'b c'。 with 'a b'。； be called the
'occipital angle；' and the angle made by the line 'a d'。 with 'a b'。 be
termed the 'olfactory angle；' and that made by 'i T'。 with 'a b'。 the
'tentorial angle；' then all these； in the mammal in question； are nearly
right angles； varying between 80 degrees and 110 degrees。 the angle 'e
f b'。； or that made by the cranial with the facial axis； and which may
be termed the 'cranio…facial angle；' is extremely obtuse； amounting； in
the case of the Beaver； to at least 150 degrees。
But if a series of sections of mammalian skulls； intermediate between a
Rodent and a Man （Fig。 28）； be examined； it will be found that in the
higher crania the basicranial axis becomes shorter relatively to the
cerebral length； that the 'olfactory angle' and 'occipital angle'
become more obtuse； and that the 'cranio…facial angle' becomes more
acute by the bending down； as it w