An endocranial cast was then made by R. J. Clarke, and the base of 

 this was smoothed and hollowed to coincide on each side with the notched 

 lower margin of the parietal bones (Figure 23). The resulting endocast 

 comprises a cast of the part of the braincase occupied by the major part of 

 the cerebrum, down to the line of recurvation of the frontal lobes anteriorly 

 and the lower margin of the occipital pole posteriorly. The parts missing 

 comprise the cast of the rostrum, the temporal lobes, the cerebellum, and of 

 the area occupied by the brainstem from about the level of hypothalamus to 

 the medulla oblongata, parts that collectively seem to occupy about one- 

 third of the total endocranial volume. 



The author, assisted by Mr. Clarke, varnished the part-cast with shellac 

 and determined its capacity by volumetric displacement of water. Eight 

 determinations were made, and results were as follows: 408, 409, 410, 410, 

 411, 411, 412, and 414 c.c. The mean of the 8 readings is 410.6 c.c. 



Once more, very similar part-casts were made from the 2 very com- 

 plete australopithecine endocasts, namely those of Sts 5 and of Old. Horn. 

 5, for both of which the total endocranial volume is known (480 c.c. and 

 530 c.c, respectively). The part-casts were made by Mr. Clarke under the 

 author's direction, the basal parts being removed along a curved line corre- 

 sponding to the lower margin of the frontal lobe impression in front and 

 of the occipital lobe impression behind. The volumes of the 2 part-casts 

 were determined by 8 volumetric displacements each. 



The 8 readings for Sts 5 were 317, 317, 317, 318, 319, 320, 321, and 

 321 c.c, giving a mean of 318.75 c.c. This value comprised 66.41 per cent 

 of the total volume of 480 c.c. (and 65.72 per cent of Holloway's estimate 

 of 485 c.c). The 8 readings of Old. Horn. 5 were 345, 349, 350, 351, 352, 

 352, 353, and 353 c.c, giving a mean of 350.625 c.c. This value comprised 

 66.16 per cent of the estimated total volume of 530 c.c. 



Thus, the 2 readings for the selected part-endocasts were extremely 

 close, namely 66.41 (or 65.72) and 66.16 per cent of the respective total 

 volumes. The total values obtained for Old. Horn. 16 on the basis of these 

 figures amounted to 618.3 c.c. and 620.6 c.c, respectively. Using the mid- 

 value between the 2 percentages, we obtained a value of 619.45 c.c. 

 For practical purposes, a value of 620 c.c. may be accepted. On Holloway's 

 estimate of 485 c.c. for Sts 5, the value for Old. Horn. 16 would be 

 624 c.c. 



Like the previous specimen, this one represents an immature indi- 

 vidual, and its cranial capacity may be expected to be about 98 per cent of 



79 ^ 



