508 



piLLAULT 1900, Paterson 1893, Regalia 1880, 1895, Rosenberg 1876, 

 1882, 1899, ScHMiD 1897, Staderini 1894, Steinbach 1889, Stru- 

 THERS 1875, SzAWLOWSKi 1901, Tenchini 1887—1889 and 1894, To- 

 PINARD 1877, Veraglia 1885 and Welcher 1881. 



A statistical study of the frequency of numerical variation in the 

 vertebrae appears first to have been taken up by Topinard (1877). 

 This investigator studied 350 skeletons in the various museums of 

 Paris. His article formulates a most valuable account of the details 

 of vertebral structure. The statistical results may be summed up as 

 follows : 



1) Spinal columns with 24 presacral vertebrae . 332, 94.9 % 



a) Normal vertebrae 318, 90.8 % 



b) Anomalies: 



Cervical 2, 0.57 o/„ 



6 c, 1 ct, 12 t, 5 1, 5 s (2) 



Thoracico-lumbar 5, 1.43 % 



6 c, 1 ct, 11 t, 6 1, 5 s 



6 „ 1 „ 11 „ 6 „ 5 „ 1 sCo 



7 „ 11 „ 6 „ 5 „ 2 Co (2) 

 7 „ 12 „ 1 tl, 4 1, 5 s 



Sacral 7, 2.0 % 



7 c, 12 t, 5 1, 6 s (6) 



6 „ 1 ct, 12 t, 5 1, 5 s, 1 sCo 



2) With 23 presacral vertebrae 8, 2.3 X 



7 c, 11 t, 5 1, 5 s 



7 „ 12 „ 4 „ 1 Is, 5 „ 



7 „ 12 „ 4 „ 1 „ 4 „ (2) 

 7 5, 12 „ 4 „ 6 „ (3) 



3) With 25 presacral vertebrae 10, 2.9 «/o 



7 c, 13 t, 5 1, 5 s 



7 „ 12 „ 6 „ 5 „ (6) 



7 „ 12 „ 6/5 „ 4/5 „ 



7 „ 12 „6 „1 Is, 4 „ 1 sCo (2) 



A decade after the publication of the monograph of Topinard, Ten- 

 chini (1887—1889) brought out several papers dealing statistically 

 with vertebral variation. To these papers, which are referred to in 

 the literature at the end of this article, I have not had access, and 

 therefore I cannot compare specifically the results of Tenchini with 

 those of other investigators. In a later paper, written in 1894, Ten- 

 chini says that in a total of 117 skeletons studied by him, vertebral 

 variation was found 10.2 per cent. 



