222 



929. A fractured fourth lumbar vertebra of the Macrauchenia patachonica : an 

 abnormal growth of bone from its posterior margin, tending to produce 

 anchylosis with the adjoining vertebrae, indicates the animal to have been 

 aged. 



From the tertiary deposits of Port St. Julian, Patagonia. 



Presented by Charles Darwin, Esq., F.R.S. 



930. A fractured fifth lumbar vertebra of the Macrauchenia patachonica : the 

 transverse diameter of the spinal canal at its anterior outlet is one inch 

 seven lines ; the vertical diameter being one inch three lines : the median 

 ridge and lateral depressions still characterize the floor of the canal. 



From the tertiary deposits of Port St. Julian, Patagonia. 



Presented by Charles Darwin, Esq., F.R.S. 



931. A fractured sixth lumbar vertebra of the Macrauchenia patachonica. 



From the tertiary deposits of Port St. Julian, Patagonia. 



Presented by Charles Darwin, Esq., F.R.S. 



932. Fragments of the neural arches of some of the preceding lumbar 

 vertebras. 



933. The anterior articular or oblique processes of some of the preceding 



lumbar vertebra?. 



934. Three fragments including the body and portions of the two transverse 

 processes of the last or seventh lumbar vertebra of the Macrauchenia 

 patachonica ; the posterior surface of each transverse process is charac- 

 terised by a large and deep transversely oval articular surface, exceeding 

 in size the intermediate articular process in the body of the vertebra ; 

 this three-fold articulation of the true with the false vertebra?, does not 

 exist in the species of the Camel tribe, but is peculiar among existing 

 Mammalia to the Horse, Hippopotamus, Tapir and Rhinoceros. 



The articulations of the body and transverse processes of the last lumbar 

 vertebra of the Macrauchenia differ, however, from the corresponding arti- 

 cular surfaces of the Horse, inasmuch as the middle surface is convex, 

 while the two lateral ones are concave, and these are moreover relatively 

 larger than in the Horse or Hippopotamus ; by this structure the trunk 



