152 
DE. J. CLELAND ON THE VARIATIONS OE THE HUMAN SKULL. 
radial measurements most likely to be useful to the craniologist, in conjunction with mea- 
surements of other kinds, are those extending to the occipital tuberosity and fronto-nasal 
suture, indicating the comparative development of the anterior and posterior parts of the 
brain. 
II. THE FACE. 
The most important points to be attended to in the measurements of the face are 
those affecting orthognathism and prognathism. The appearances so termed form the 
basis of a fundamental part of the classification of crania generally recognized, and in 
recent years it has been sought more explicitly to divide them by adding a third term 
and distinguishing opisthognathous skulls ; yet it will not be hard to show that the opi- 
nions entertained by anatomists as to the causes which concur to produce these appear- 
ances are both vague and inaccurate. 
So far as prognathism depends on the forward direction of the incisor teeth, or what 
may be designated prognathous dentition, it is simple enough and affords a stable foun- 
dation for classification ; but besides that this is only one of the characters of progna- 
thism originally enunciated by Retzius, the term is always considered as indicating pro- 
jection of the face from underneath the cranium. 
The broad contrast between the straight European face and the prominent muzzle 
of many savage tribes was evidently present alike to Camper in suggesting the facial 
angle, to Blumenbach in laying down the advantages of the norma verticalis, and to 
Retzius in distinguishing orthognathous and prognathous skulls; but these methods 
leave unexplained the nature of the anatomical peculiarities producing the appearances 
sought to be registered. Virchow* stepped forward, and estimating prognathism by the 
size of an angle, the “nasal angle,” situated at the fronto-nasal suture and contained 
between two lines, one passing down to the nasal spine, and the other back to the pos- 
terior limit of the sphenoid bone, he laid down the rule that the shorter the base of the 
skull, and the more curved on itself, the more the face projected from underneath it. 
Lucae f, taking the zygomatic arch as a horizontal line, and drawing a perpendicular 
to it from the fronto-nasal suture, estimated the retreat of the forehead and the projec- 
tion of the face by horizontal lines drawn from points in them and cutting the perpen- 
dicular at different heights, and concluded that there was no relation whatever between 
the form or extent of the base of the skull and the projection of the face. Then 
Welcker J, choosing a nasal angle which differed from that of Virchow in that the upper 
of its containing lines passed from the fronto-nasal suture back to the foramen magnum, 
put forward the statement that the base of the skull and the projection of the face 
were indeed in relation, but that the relation was precisely the reverse of that stated by 
Virchow. Landzert§ agrees with Virchow that the nasal angle and the angula sellse 
exhibit an inverse ratio one to the other ; but, appreciating that the nasal angle is no 
* Entwicklung des Schadelgrunde, 1867. f Op. cit. p. 40. 
j "VVachsthum und Bau des mensckliclien Schadels, 1862, pp. 48 & 140. 
§ Der Sattelwinkel und sein Verkaltnisa zur Pro- und Ortliognathie, 1867. 
