122 
THE VOYAGE OF H.M.S. CHALLENGER. 
drawn from the basion through the basi-occipital and sphenoid bones to the sphenoido- 
ethmoid articulation in the anterior cerebral fossa, forms with a line from the same point 
in the sphenoido-frontal articulation drawn parallel to the cribriform plate of the ethmoid 
through the upper end of the ethmo-frontal suture. These lines, which I shall call the 
basi-occipito-sphenoid axis and the cribriform axis, and the angle formed by their inter- 
section, the sphenoido-ethmoid angle, have been studied by Prof. Huxley, 1 and to the first 
of the two lines he has given the name of basi-cranial axis. Almost similar lines have 
also been drawn by Prof. Cleland 2 and named by him the middle base and the frontal 
base, whilst the plane of the foramen magnum he regards as the hindmost division of the 
base of the skull. The length of these lines expressed in millimetres and the angle 
formed by their intersection in the same skulls as those measured in Table XVIII. are 
given in Table XIX. The angle which the basi-occipito-sphenoid axis forms with the 
plane of the foramen magnum is named the foramino-basal angle in the same Table. 
Table XIX. (Plates VI, VII.) 
r 
Bush. 
Fuegian. 
Admir- 
Oahu. 
Hawaii. 
Hew 
Chatham 
Aus- 
Aus- 
Aus- 
Collection, -J 
Umzim- 
kulu. 
A. 
alty 
Islander. 
A. 
D. 
B. 
Zealand. 
Waikato. 
Island. 
A. 
tralia. 
Queens- 
land. 
tralia. 
Gipps- 
land. 
tralia. 
Basi-occipito-sphenoid axis, . 
59 
64 
64 
66 
65 
69 
70 
59 
55 
63 
Cribriform axis, 
Sphenoido-ethmoid angle, 
28 
29 
30 
22 
21 
21 
24 
34 
28 
28 
142° 
139° 
148° 
148° 
147° 
154° 
150° 
136° 
138° 
138° 
Foramino-sellar angle, . 
126° 
125° 
115° 
123° 
130° 
140° 
132° 
129° 
124° 
127° 
Foramino-basal angle, 
147° 
138° 
143° 
140° 
146° 
151° 
146° 
157° 
139° 
150° 
Spheno-maxillarv line, . 
72 
79 
72 
73 
69 
72 
79 
79 
72 
85 
Spheno-maxillary angle, 
94° 
89° 
90° 
101° 
93° 
92° 
91° 
91° 
93° 
93° 
Base line, .... 
136 
137 
128 
140 
135 
135 
144 
130 
127 
136 
Frontal chord, 
113 
109 
121 
113 
113 
112 
122 
118 
102 
108 
Parietal ,, 
113 
111 
127 
104 
114 
106 
108 
121 
115 
119 
Occipital ,, . 
91 
103 
96 
111 
103 
96 
103 
99 
87 
91 
The basi-occipito-sphenoid axis is not necessarily parallel to the plane of the surface 
of this part of the cranial base, i.e., to the dorsum sellse, so that the angle which it makes 
with the plane. of the foramen magnum does not express how far the slope of the dorsum 
sellse approaches or departs from the perpendicular radius. I have accordingly drawn a 
line parallel with the dorsum sellae to cut the plane of the foramen, and have inscribed 
the angle formed by their intersection in Table XIX. as the foramino-sellar angle. It 
will be seen that the inclination of the dorsum sellse to the plane of the foramen magnum 
exhibited a considerable range of variation in the series of crania measured. In the 
Admiralty Islander it approached closer to a right angle than in any of the others, whilst 
in the New Zealander it opened out to 140°. Very little variation in the foramino-sellar 
angle occurred in the three Australian skulls. The foramino-basal angle formed by the 
1 Two widely contrasted forms of Human Skulls, Journ. Anat. and Phys., November 1866. 
2 Description of a Sulu skull, Journ. Anat. and Phys., July 1877. 
