146 



THE BIOLOGY OF TWINS 



Set C 30 (Fig. 50). The mother has in band i a 

 double scute two places from the right margin, and 

 fetuses II, III, and IV have each a double scute two 

 places from the left margin of the same band. 



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Fig. 48 



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Fig. 49 



Figs. 47, 48, and 49. — Showing the incidence of scute doubling in 

 sets K 27, C 26, and C 76, respectively. (Details in text.) 



Mirror-imaging among the fetuses of a set. — It is 

 very common to find symmetry reversals within a set 

 of quadruplets involving what we call mirror-imaging. 



Set C 30 (Fig. 50). Fetus I has a pecuhar type of 

 scute three places from the right margin of band i, 



