424 PRINCIPAL SIR WM. TURNER ON 



the general lumbar index showed that the posterior vertical diameters collectively were 

 longer than the anterior, though in my example the difference in favour of the posterior 

 was only 2 mm. ; but it should be noted that the low index, 84, of the body of the 5th 

 lumbar expressed for that vertebra a definite wedge shape, with the base of the wedge 

 in front. 



In my Challenger Report I discussed the question of the part taken by the lumbar 

 bodies in the production of the lumbar curve in the human spine. I showed that in 

 Europeans, whilst the 1st and 2nd vertebrae had the posterior vertical diameter longer 

 than the anterior, in the 3rd, 4th, and 5th vertebras the anterior diameter was the longer, 

 the mean general lumbar index was 96, almost identical with the mean 95 "8 obtained 

 by Cunningham in measuring a larger number of European spines. In their lumbar 

 region, therefore, it was obvious that the collective vertical diameter of the bodies was 

 longer anteriorly than posteriorly, and that if their upper and lower surfaces were 

 apposed to each other, without the interposition of discs, the lumbar curve was convex 

 forwards. To this condition I gave the name Kurtorachic. 



In my series of skeletons of the black races the collective vertical diameter behind 

 was longer than in front, and the general lumbar index in the Australians was 106, in a 

 Bushman 106, and in Sandwich Islanders 104. Both in the Australians and Sandwich 

 Islanders, as in the Tasmanians, the upper four lumbars had the posterior vertical 

 diameter greater than the anterior. In the Andaman Islanders and Negroes, however, the 

 general index was 99, and in the 1st, 2nd, and 3rd lumbars only was the posterior vertical 

 diameter greater than the anterior. Cunningham obtained similar results in Australians, 

 Bushmen, Andaman Islanders, and Negroes, in which races the general lumbar index 

 was, he stated, 104 and upwards. I found in my specimens, where the lumbar bodies 

 were apposed to each other, without the interposition of discs, that the lumbar spine 

 was concave forwards as low as the interval between the 4th and 5th lumbars, and to a 

 spine in which this character was exhibited I gave the name Koilorachic. Tested in this 

 way, the Tasmanian skeleton described in this memoir belonged to that group.* 



In the study of the production of the lumbar curve in the complete spine the 

 bodies of the vertebras are not the only factors concerned, for the form and thickness of 

 the intervertebral discs have to be considered. There can be no doubt that in 

 Europeans the discs materially contribute to the production of the prominent lumbar 

 convexity. This was proved many years ago by the brothers Weber, who in their 

 inquiry showed that the anterior surfaces of the discs, between the 12th dorsal and the 

 1st sacral, were collectively 21 '1 mm. more in vertical diameter than the posterior, and 

 that the disc between the 5th lumbar and 1st sacral took a special share, so that the 



* As a sequel to the observations of Cunningham and myself on the relation of the vertical diameters of the 

 bodies of the lumbar vertebra; to the lumbar curve, George A. Dorsey conducted a research on 85 skeletons of North 

 American and Peruvian Indians {Bulletin Essex Institute, Salem, Mass., vol. xxvii., 1895). He obtained a mean 

 general index, LOO'S). In the 1st, 2nd, 3rd, and sometimes the 4th vertebra the posterior vertical diameter exo 

 the anterior, but in the 5th lumbar the anterior was the longer. Dorsey places the Indian spines in the group which 

 I named Orthorachic, where the index ranged from 98 to 102. 



