( 529 ) 
Lemur. 40. Propithecus 42. 
Mycetes. (18). 33. 45. 53. 59. Average 47.5. 
Pithecia. 54. 56. 60. 64. Av. 58.5. 
Hapale. 61. 61. 63. 64. 69. 72. Av. 65. 
Chrysothrix. 60. 61. 63. 65. 66. 69. 70. 70. 71. 71. Av 66.6. 
Cebus. 63. 64. 64. 65. 67. 67. 68. 72. 73. 75. Av. 67.8. 
Ateles. 66. 67. 68. 71. 77. 79. 82. Av. 72 7. 
Cynocephalus. 63. 64. 66. Av. 64.2. 
Inuus. 66. 68. 70. 76. 76. Av. 71.2. 
Macacos <?. 68. 70. 70. 74. 79. Av. 72.2. 
Maeaeus 2. 67. 73. 75. 78. 84. Av. 75.4 
Cercopithecus. 74. 80. 81. 82. Av. 79.2. 
Colobus. 64. 72. Av. 68. 
Semnopithecus. 60. 61. 61. 64. 68. Av. 62.8. 
Siamanga. 55. 56. 56. 56. 58. 61. 63. 63. 67. 68. Av. 60.2. 
Hylobates. 52. 60. 66. 73. 75. Av. 65.1. 
Chimpanzee. 64. 79. 80. Av. 74.3. 
Gorilla. 63. 63. 66. 70. 76. 77. 80. 80. Av. 71.8. 
Orang. 58. 62.' 68. 70. 72. 75. 79. 80. Av. 70.3. 
These figures show in the first place that the slope of the Foramen 
magnum varies greatly in individual cases, a fact which is apparent 
by merely looking at the skulls. This individual variability is espe- 
daily noticeable in the large skulls such as those of the Anthropotds. 
And yet the general configuration of the skull is but little influenced 
by these great variations in the slope of the Foramen. As a proof 
Fig. 2. 
Mycetes. (*/*) Angle of inclination of the For. magn. 18°. 
of this, I have given in Figs. 2 and 3 the mediagiams of two 
Mycetes skulls, with slope-angles of 18 and 59 respective y. 
From the figures it can also be seen that a slight shortening of 
the Clivus is of great influence on the angle of the slope. Now 
