OCCURRENCE OF TWINS 179 



than once ended in a refusal to supply any details at all. 

 Even when information as to sex has been obtained, it has 

 not always been considered worth recording here ; for in 

 the interests of accuracy not only should this be given in 

 the diagram, but the chart should at the same time display 

 the exact position in which the individual comes in the 

 sequence of births, so far, of course, as the statements of 

 the relatives, or whoever else the details are being gathered 

 from, may be relied on in the matter. 



Pedigree D. 



In this pedigree may be found the details of the 

 descendants of two allied stocks (A. 1 and 2, 3 and 4), 

 each of which shows a strong tendenc}^ to plural births. 



In the family of A. 1 and 2, there were quadruplets in 

 Generation B. among seven persons* ; in Generation C. 

 (omitting the offspring of No. 7 B.) there were three pairs 

 of twins among ten individuals, and in Generation D. 

 twins occurred once among some seven children. Among 

 the grandchildren and great-grandchildren of A. 3 and 4 

 (omitting the descendants of B. 8) twins occurred once 

 and twice respectively out of eight and fourteen 

 children. 



The branch produced by intermarriage of these two 

 families, and which begins with Generation B, 7 and 

 8, gave birth, out of a total of seventeen descendants, to 

 three pairs of twins, all of whom appear in Generation D. 



To put it in another May, in the common stem and 

 among its collaterals on both sides of the house, there 

 have been no fewer than eleven plural births in these 

 three generations. 



Explanation of Pedigree D. 



The symbols, letters, and numbers have the same 

 significance as in the other Pedigrees of Twins, but Q. here 

 means quadruplets. 



General Remarks on the Four Pedigree Charts. 



Each of the four families, the details of which are 

 displayed on the accompanying charts (A — D), is selected 

 as giving a different aspect of the subject with regard to 



* The quadruples did not live. 



