304 CHARLES B. STOCKAKD AND A. L. JOHNSON 



Plate 57 (p. 321) presents a series of fourteen F 2 skulls, 

 and a mere casual examination of these will indicate how 

 very different each of the fourteen is from the others. 



The last column in table 4 gives the records of skull measure- 

 ments for baekcross hybrids from the F x on the English 

 bulldog. The indices for these baekcross bulldog skulls, as 

 would be expected, approach more nearly the pure bulldog- 

 values than do the other hybrid measurements. Yet in those 

 features for which the bulldog skull is extreme, the baekcross 

 from the F, on the bulldog deviates considerably from the 

 pure parent type. 



In order to make further comparisons among the indices 

 and features of individual skulls in contrast with comparisons 

 of average conditions, we have plotted charts for several 

 of the bulldog-bassethound indices, and these will be dis- 

 cussed in the following section. 



Indices and Proportions in Individual Skulls from the 

 Bassethound-Bulldog Cross 



Several different indices for the individual skulls of the 

 bassethound-bulldog cross are indicated in text-figures 65 to 

 68. The upper chart in text-figure 65 gives the cranial index 

 values. The three bassethound skulls have values of 61, 

 67 and 68, a range of 7 units, while the eight bulldog skulls 

 range from an index of 58, which is lower than any for 

 the bassethound, up to a high index of 80. The cranial 

 index in the bulldog has a range of 22 units, roughly three 

 times greater than the range for the bassethound skulls. 

 However, three of the eight bulldog skulls show less range 

 for this index than do the three bassethound skulls, and one 

 might be justified in concluding that if more skulls were 

 represented, the cranial index of the bassethound might be 

 as widely variable as it is in the bulldog; but on the basis 

 of measurements from many living animals we know this 

 to be untrue. The bulldog cranium varies in its shape much 

 more widelv than does the cranium of the bassethound. 



