﻿I860.] 



HUXLEY — MACEA UCHEXIA BOLT VIENSIS. 



83 



This backward extension of the palate is, so far as it goes, in 

 favour of the view to which the consideration of the dentition and 

 the structure of the occiput leads, viz. that the cranium of the 

 Macrauclienia was constructed upon an essentially Artiodactyle type. 



The following are the dimensions of the palate and teeth of Ma- 

 crauclienia Boliviensis, and those of the corresponding parts in the 

 Vicugna : — 



The narrower palate of the Macrauclienia agrees with its narrower 

 occiput, while it exhibits the same general correspondence with the 

 Vicugna as has been met with in the limbs and vertebras. 



Thus I conceive that an attentive examination of these scanty 

 remains is sufficient to prove that, when they were imbedded, there 

 lived in the highlands of Bolivia a species of Macrauclienia not half 

 as large as the Patagonian form, and having proportions nearly as 

 slender as those of the Vicugna, with even a lighter head ; and it is 

 very interesting to observe that, during that probably post-pleistocene 

 epoch, a small and a large species of more or less Auchenoid 

 Mammal ranged the mountains and the plains of South America 

 respectively, just as at present the small Vicugna is found in the 

 highlands, and the large Guanaco in the plains of the same con- 

 tinent f. 



The structure and geological date of the genus Macrauclienia may 

 serve, if taken together, to point an important palasontological moral. 

 Professor Owen, in the able memoir cited above, has clearly pointed 

 out the remarkable combination of Artiodactyle and Perissodaetyle 

 characters exhibited by Macrauclienia, which unites the eminently 

 characteristic cervical vertebras of the Artiodactyle Camelidce with 

 the three-toed fore foot and the triply trochantered femur of the 



average it is doubtless true that the bony palate extends further back in the former 

 than in the latter ; but the bony palate extends to a line joining the anterior 

 edges of the last molars in Tlyrax ; while in the full-grown Gruanaco, a similar 

 line is 04 of an inch behind the posterior boundary of the palate. 



* The six grinding-teeth of the lower jaw, which Professor Owen has provi- 

 sionally referred to Macrauclienia (British Association Eeports, 1846), are said 

 to form a series 9 inches long. A series of six such teeth of the lower jaw 

 of Macrauclienia Boliviensis could not have exceeded 4 inches in length, and 

 was probably shorter. Under these circumstances, the heads (as measured by the 

 teeth) of the two species would be in nearly the same proportion as then' 

 astragali, and in very different proportions from their cervical vertebrae. This is 

 not improbable ; for the Vicugna has a much lighter head than the Guanaco, if the 

 cervical vertebras be taken as the standard. The length of the fourth cervical of 

 the Vicugna is to that of the same bone in the Gruanaco as 1 : 1 T , while the length 

 of the head in the two is as 1 : 1^. 



f As the Gruanaco ranges into the highlands, it may not be a too sanguine 

 expectation to hope for the future discovery of remains of the great Macrauclienia, 

 also, in Bolivia. 



Macrauclienia. 



Vicugna. 

 1-25 (at widest). 



2-2 



g 2 



