GENETIC TYPE AND THE ENDOCEINES 315 



for the breadth-height index. These same backcross skulls 

 also showed no differences for cranial indices in the upper 

 chart of text-figure 65. The breadth-height index and the 

 cranial index charts both show that there are no consistent 

 genetic differences between the cranial proportions of the 

 bassethound and the bulldog, and this means that the measure- 

 ments concerned do not involve the base of the cranium in 

 a consistent manner. 



Curves have been plotted in text-figure 69 to indicate the 

 average of the index values for the individual skulls given 

 in the foregoing charts. The average for the bassethound 

 indices is represented by the solid line, for the bulldog by 

 the dash-dot line, for the F x by a dashed line, and for the F 2 

 by a dotted line. The several indices and the proportions rep- 

 resented by the curves are listed at the bottom of the chart 

 immediately below the points on the curves which indicate 

 their values. 



The average indices for the bulldog and bassethound skulls 

 show the cranial index in the two breeds to be only 5 points 

 apart and the breadth-height index slightly more. These are 

 the only two upper cranial proportions shown. 



The averages for total skull index, palatal index and snout 

 index place the two skull types increasingly far apart. The 

 curves for snout index averages are separated by 110 units, 

 the widest divergence shown. The reversed upper facial index 

 shows a difference of 64 units between the two skull types. 



The several regional proportions as designated below the 

 curves show only slight differences, except in the case of the 

 relation between the total anteroposterior width of the maxil- 

 lary premolar teeth and the anteroposterior extent of the 

 premolar region. The bassethound and bulldog skulls differ 

 from one another for this proportion by 33 units of per- 

 centage. 



The curves for averages of indices and proportions in the 

 F x skulls almost invariably lie closer to the bassethound 

 averages than to those of the bulldog, and this is particularly 



