44 
Proceedings of the Royal Society of Edinburgh. [Sess. 
Our choice of a base line was determined, as it was in Schwalbe’s work, 
by the fact that in Dubois’s Pithecanthropus (10) the nasion was absent, 
and consequently our working base line became the glabella-inion length. 
Klaatsch (3), too, employs the same base line for the same reason and 
the like object. He says : “ With regard to the Pithecanthropus, Spy, and 
Neanderthal remains, I followed Professor Schwalbe in taking for a 
common horizon the plane passing through the glabella and inion.” And 
again, “ for purposes of more precise comparative investigations with the 
fossil fragments, the glabella-inion line is clearly preferable.” 
Turner (11), on the other hand, in his 1908 work on ten Tasmanian 
crania, employs a “ nasio-tentorial plane drawn from the nasion to the upper 
border of the groove for the lateral sinus, which divided the cranial cavity 
into a cerebral part above this plane, and a basal part for the lodgment 
of the cerebellum, pons, and medulla.” His reason for the selection of this 
plane as opposed to the glabella-inion plane is that “ the range of variation 
in its projection (that is, the glabella), associated in a more or less degree 
with the development of the frontal sinuses, unfits it to be used for taking 
the point in front from which to estimate the length of the cerebral part 
of the cranial cavity.” 
We agree with Turner that the glabella-inion plane is not the best 
“ from which to estimate the length of the cerebral part of the cranial 
cavity,” for in our own experience we have found the nasio-inion plane 
coincides more closely with the length of the cerebral part of the cranial 
cavity than either the glabella-inion or nasio-tentorial planes. The nasio- 
inion plane is not, however, used in the present investigation, for the 
sufficiently adequate explanations already given ; but in the second part 
of this work, that is, the comparison of 100 Australian aboriginal crania 
with the Tasmanian crania and with those of primitive man, both nasio- 
inion and glabella-inion planes will be employed. 
Such being the reasons which determined, for the present investigation, 
the choice of the glabella-inion plane as a base line, it is next necessary to 
say something as to the locations of the anterior and posterior ends of the 
plane, that is, of the glabellar point and the inion. 
The glabellar point has been defined by a large number of authors, as 
is fully set forth and discussed by Schwalbe (2). Klaatsch (3) simply says 
the “ glabella is the most prominent surface of the forehead in the median 
line between the superciliary ridges.” 
Schwalbe (2) defines the glabellar point, that is, the anterior end of the 
glabella-inion plane, in this way: “ Da die Glabella auf derri Medianschnitt 
durch eine Curve dargestellt wird, so ist es nothig, einen Punkt derselben 
