223 



was more firmly locked to that segment of the vertebral column which 

 receives and transmits to the rest of the body the motive impetus given 

 by the hinder extremities, which are in all quadrupeds the chief powers 

 in progression on dry land ; while at the same time the shock must have 

 been diminished by the great extent of interposed elastic cartilages ; and 

 a certain yielding or sliding motion would be allowed between the lumbar 

 vertebrae and sacrum. 



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



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



935. Fragments of the pelvis including the two convex articular surfaces on the 

 transverse processes of the anterior sacral vertebra, adapted to the con- 

 cavities on those of the posterior lumbar vertebra ; and a small portion 

 of the acetabulum. 



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



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



936. Fragments of the left scapula of the Macranchenia patachonica. 



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



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



The acromion commences about half an inch behind the glenoid cavity, 

 and rises at once to the height of three inches above the plane of the sca- 

 pula, in which structure we may trace the same tendency to the Ruminant 

 type as is manifested in the scapula of the Hippopotamus and Anoplothe- 

 rium ; for in most other Pachyderms the spine increases gradually in height 

 from both its extremities to the middle part. The anterior margin of 

 the spine beneath the short acromion is perforated by an elliptical fissure 

 measuring ten lines by three lines. The extent of the spine which is 

 preserved measures eight inches and a half: it is a thin and nearly 

 straight plate of bone, expanding into a thick and rugged upper margin, 

 which slightly overarches the inferior fossa. 



In its general form and proportions the spine of the scapula in the 

 Macrauchenia presents the nearest resemblance to that of the Hippopo- 

 tamus ; but its origin is closer to the articular surface of the scapula 

 than in this or any other Pachydermal or Ruminant animal. 



