218 



lating folds ; but its general disposition most resembles tbat in the 

 inferior molars of the Rhinoceros. The teeth of the Elasmotherium differ 

 from those of the Rhinoceros, and resemble those of the Horse in the 

 great depth to which they are implanted in the jaw, before being divided 

 into roots : the socket of the penultimate grinder extends, in fact, to 

 the lower margin of the jaw without any indication of partitions for 

 the lodgement of fangs : there is no trace of incisive teeth in the portion 

 of symphysis which is preserved, and which extends a little more than 

 three inches in advance of the first small molar. 



The original of this specimen is preserved in the Museum of Moscow, 

 and is unique ; it was discovered in the frozen drift or diluvium of Siberia. 



Presented by R. I. Murchison, Esq., P. G.S. 



Genus Macrauchenia*. 



924. The third or fourth cervical vertebra of the Macrauchenia patachonica, 



Owen. The anterior articular end of the body has been broken off, and 

 the anterior orifices of the canals for the vertebral artery may be seen 

 close to the inner surface of the neural arch, on the, fractured end of the 

 vertebra. 



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



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



925. The fourth or fifth cervical vertebra of the Macrauchenia patachonica; want- 



ing the posterior articular processes : both the entry and the outlet of the 

 characteristic intra-spinal canal for the vertebral artery may be observed 

 on the inside of the neural arch, in the angle between it and the body of 

 the vertebra on the right side. 



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



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



925'. The fourth cervical vertebra of a Llama {Auchenia Glamd) ; to show 



its correspondence in general form and structure with the cervical 



vertebra of the Macrauchenia, and especially in the position of the canals 



for the vertebral arteries, which canals perforate the neural arch and 



* [xatcpos long, av^rjv neck. 



