GENETIC TYPE AND THE ENDOCRINES 167 



picture. There is absolutely no correlation between these 

 two measurements in this series of skulls. We conclude, 

 therefore, that in the skulls of the different dog breeds no 

 two of these three cranial width measurements follow any 

 close accord. 



A comparison of cranial height and width measurements 

 among different breeds. The relation of height to width in 

 the mammalian cranium is of considerable significance. A 

 high, wide cranium usually means a large brain, but in the 

 final analysis the size of the brain depends, of course, upon 

 cranial length as well. The cranial index, as discussed in a 

 later section of this paper, is of interest in connection with 

 these height to width comparisons. 



The height of the cranium is indicated in these measure- 

 ments by the straight distance between the orifice of the 

 auditory meatus and the bregma, that point on the sagittal 

 line where the parietal and frontal bones meet (pi. 35, fig. 3, 

 0-0). In addition to height, an element of width is partially 

 involved in this measurement, but height is the larger factor. 



In text-figure 16, measurements on this group of seventy 

 skulls were arranged in sequence from the longest to shortest 

 straight distance from auditory meatus to bregma. These 

 distances range from 73 mm down to 41 mm, the extremes 

 being to one another as 7:4. This difference is not great in 

 view of the fact that both giant and midget dog skulls are 

 included. A curve drawn along the tops of the lines in this 

 chart forms a regular and quite gentle slope, the only sharp 

 fall being between the sixth and seventh dimensions. 



It is quite evident from a comparison of this chart with 

 text-figure 17, which shows least frontal widths in the same 

 sequence, that there is no correlation between cranial heights 

 and least frontal widths. The six very high crania indicated 

 at the left in text-figure 16 are equalled or surpassed for 

 their frontal widths by ten skulls scattered almost throughout 

 the series in text-figure 17. The range of measurements for 

 least frontal widths is almost identical with that for cranial 



