The ratio of the total pooled female mean to the total pooled male 

 mean is 85.2 per cent, very similar to that for the pooled orangutan series 

 (86.2 per cent). Again, there is a fairly wide spread of sample sex ratios, 

 the values for which are 88.2 (Selenka), 84.9 (Randall), 83.6 (Ashton and 

 Spence), and 82.8 (Schultz). The series of the other 4 workers cited in Table 

 7 are excluded from this comparison as the size of the female sample in each 

 instance is too small. 



The mean for 414 pooled male gorillas is exactly 100 c.c. greater than 

 that for 203 pooled male orangutans (534.6 c.c. against 434.4 c.c). In the 

 female series the pooled gorilla mean (455.6 c.c.) exceeds the pooled orang- 

 utan mean (374.5 c.c.) by 81.1 c.c. 



Schultz (1962) published a mean for 58 West African male gorilla 

 crania, the capacities ranging from 423 to 752 c.c. with a mean of 536.1 c.c. 

 These data are not cited separately in Table 7, as the 58 crania are in- 

 cluded in Schultz's (1965) series of 72 male gorilla crania. 



The value of 752 c.c. is the only gorilla capacity or ape capacity ever 

 to have been measured in excess of 700 c.c. Schultz (1962) tells us that he 

 measured the capacity of this cranium (No. 6841) extremely carefully, 4 

 times, with practically the same result. He made a meticulous search for 

 signs of pathology but concluded that the animal was normal. The cranium 

 belonged to a young adult male animal that had been shot in the wild on the 

 northeastern frontier of Spanish Guinea in i960. 



This maximum capacity of 752 c.c. is exceptional, exceeding the pre- 

 vious gorilla maxima of 605 c.c. (Gyldenstolpe 1928), 623 c.c. (Weidenreich 

 1943), 642 c.c. (Harris 1926), 655 c.c. (Hagedoorn 1926), and 685 c.c. (Ran- 

 dall 1943-1944). 



Summation on mean cranial capacities. Table 8 is a brief summary 

 of mean cranial capacities in living hominoids. 



Table 8: Summary of mean cranial capacities in living male and 

 female hominoids: latest pooled data (in c.c.) 



Males Females 



Gibbon (H. lar) 104.0 (n = 95) 100.9 (n = 85) 



Siamang (S. syndactylus) 125.8 (n = 23) 122.8 (n = 17) 



Chimpanzee (Pan troglodytes) 398.5 (n = 163) 371.1 (n = 200) 



Orangutan (Pongo pygmaeus) 434.4 (n = 203) 374.5 (n = 199) 



Gorilla (G. gorilla) 534.6 (" = 414) 455.6 (n = 254) 



% 40 



