VARIATION AND HEREDITY IN TWINS 145 



doubling, evidently inherited from the father, since 

 the mother showed none, could be confined to the two 

 fetuses and excluded from the other two, when all came 

 from the same fertilized egg. 



Data on the inheritance of scute doubling. — Scute 

 doubhng is far more frequent in its incidence than band 

 doubling, but the modes of inheritance and distribution 

 are the same. Band doubling may be inherited as 

 scute doubling, or vice versa. A few examples of the 

 inheritance of scute doubhng will be sufficient to illus- 

 trate the principles involved. Impressive cases of 

 resemblance between mother and offspring and among 

 the quadruplets of a set are of frequent occurrence. 



Set K 27 (Fig. 47) is one of the most remarkable 

 cases of exact inheritance. The mother has two double 

 scutes located in definite places in two different bands. 

 One of the oft'spring (fetus I) has two identical double 

 scutes in exactly the same places in the same two 

 bands as in the mother. The other three fetuses are 

 without any doubling. 



Set C 26 (Fig. 48). The mother has a double scute 

 of a peculiar kind two places from the left margin of 

 band 2. The paired fetuses (III and IV) each have 

 identical double scutes in exactly the same position in 

 band i. 



Many other cases occur of close resemblance between 

 mother and offspring involving, however, a reversed 

 symmetry. An example will illustrate this: 



Set C 76 (Fig. 49). The mother has in band 6 a 

 double scute five places from the left margin. Fetus 

 III has a similar double scute in band 4 five places 

 from the right margin. 



