494 Dr. D. J. Cunningham. 



It is this obliquity of the last lumbar vertebra in the Australian, 

 which has the effect of so nearly placing the first sacral vertebra in 

 the line of the axial lumbar curve. 



In Troglodytes the last lumbar vertebra* is closely associated with 

 the sacrum. This constitutes a striking character of the column 

 when seen in mesial section. At first sight the vertebra in question 

 appears to belong to the sacrum. The intervertebral disk which 

 intervenes is very thin ; indeed, in a young specimen, it is not much 

 thicker than those interposed between the sacral elements, and it 

 cannot be compared for a moment with the thick pads between the 

 lumbar vertebrae. This intimacy of relationship is still further borne 

 out by the examination of the macerated skeleton, because it is 

 extremely common to find the last lumbar vertebra either fixed to the 

 sacrum by osseous union, or taking on sacral characters by the 

 assumption of the characteristic sacral alee or rib elements. Of the 

 twelve skeletons of Troglodytes, in which the lumbo-sacral region is 

 mentioned in the catalogue of the Museum of the Royal College of 

 Surgeons in England, seven are described as presenting this pecu- 

 liarity. 



In the European and in the Australian, the last lumbar vertebra 

 is separated from the sacrum by a thick pad of intervertebral 

 substance. Nevertheless, we occasionally find in the human spine 

 the last lumbar vertebra either fused to the sacrum or developing on 

 one or both sides a sacral ala. Professor Kollman, of Basel, has 

 recently exhibited at the Anatomische Gesellschaft at Wiirzburg 

 (May, 1888), a series of specimens in which the different gradations 

 of this anomaly were illustrated.f During the last four or five years 

 about seventy-five sacra aud last lumbar vertebrae have been ex- 

 amined in the macerated state in the Anatomical Department of 

 Trinity College. From these I have obtained one specimen in which 

 the fusion between the last lumbar and first sacral vertebrae is almost 

 complete, and three fifth lumbar vertebrae with a sacral ala developed 

 on one or both sides. We have little information on this point in so 

 far as the spines of the low races are concerned ; but it is somewhat 

 significant that in five Australian and in two Andaman skeletons, 

 Sir William Turner J should have recorded the occurrence of three 

 fifth lumbar vertebrae with sacral alee developed upon their transverse 



* The vertebral formula being considered as C 7 , D 13 , L 4 , 8 5 , C 4 . 



f Since writing the above, I have received a letter from Professor Kollman upon 

 this subject. He informs me that he observed the anomaly in eight out of forty- 

 five specimens which he examined. In three cases the assimilation was complete 

 (i.e., on both sides), and in the remaining five it was confined to one side. His 

 specimens were all derived from European skeletons. 



I ' Zoology of the Voyage of H.M.S. " Challenger," Part XLVII.' " Eeport on 

 the Human Skeletons, Part II." 



