The B. twins were born on Christmas Day, 1914, the mongol girl having been born first at 3:15 a. m., and the normal boy twenty hours later, both being delivered instrumentally.
In their work on mongolism, Brousseau and Brainerd cite thirty-two cases in one of twins; of these, fourteen were of unlike sex, and in only six of the latter group was the girl a mongol and the boy normal, making this case the seventh of its kind to be reported.
McLean1 reported a case of mongolism in one twin with photographs showing the twins at 6½ months. In this case the boy was the mongol, and the condition was very evident. In figure 1, taken when the B. twins were between 7 and 8 months of age, it will be noticed that the difference is much less marked than in McLean's case, the mongol girl being the farthest from the mother in the picture.