EEPORT ON THE BONES OF THE HUMAN SKELETON. 
66 
of the laminar part of the neural arch independently of the pedicular part occurs, for 
observations on a sufficiently large number of specimens have not yet been systematically 
conducted. But this may without doubt be affirmed, that in a series of spinal columns 
from white races equal in number to those analysed in this chapter, and like them 
taken without selection, there would not have been found so large a proportion in which 
the 6th cervical spine was not bifid and nearly equal in length to the spine of the 7th 
cervical ; or three skeletons with a supernumerary dorsal vertebra ; or seven specimens of 
irregularity in the development of the neural arch of the 5th lumbar vertebra. 
The Lumbar Curve of the Spinal Column. 
In the course of the investigations into the characters of the skeletons described in 
this Eeport, I have measured the bodies of the lumbar vertebrae with the view of 
ascertaining if modifications existed in their vertical diameter, anteriorly and posteriorly, 
which might afi'ect the lumbar curve of the spine. 
Anatomists are in the habit of teaching that the human spine is convex forward in the 
lumbar region, so that a lumbar convexity is interposed between the thoracic and sacral 
concavities, and contributes to the alternating series of concavo-convex curves of the spinal 
column, which are associated with the erect attitude of man. My belief in the universality 
of the view that the lumbar vertebrae themselves invariably produce a forward convexity 
in that region was disturbed some years ago, when Charles Eobertson, Esq., of the Oxford 
Museum, showed me the skeleton of an aboriginal Australian in that museum, which he 
had articulated in 1873. Mr. Eobertson told me that the skeleton was that of an adult 
male of the Tomki tribe of the Eichmond Eiver, N.S.W. In it there was a continuous curve, 
concave forwards through both thoracic and lumbar regions. As the skeleton was, how- 
ever, artificially articulated, the question naturally arose in one's mind if this modification 
in the lumbar curve might not have been produced by some peculiarity in the method 
of articulation, and was not therefore natural to the spine. Since I saw this skeleton, 
however, Mr. Eobertson has written to tell me of another adult male from Port Augusta, 
South Australia, articulated in 1878 with great care and with especial attention to the 
lumbar curve, which exhibited a similar concavity in the lumbar region, and that the 
articulated skeletons of a Gilbert Islander and a male Andaman Islander have a similar 
lumbar concavity, though not so well marked. Before I had heard, however, of these 
later specimens in the Oxford Museum, I had examined the lumbar vertebrae in the series 
of spines at my disposal in Edinburgh, and had obtained some interesting results. 
Two important factors contribute to the curve in the lumbar region, viz., the 
vertebral bodies and the intervertebral discs. The exact share contributed by each of 
these parts can only be ascertained with precision by applying to the vertebral column in 
the different races of men the method of observation which Professor D. J. Cunningham 
(zooL. CHALL. EXP.— PART XLVii. — 1886.) Aaa 9 
