Februaky 1, 1894.] 



KNOWLEDGE 



29 



so termed on account of the elongation of the vertebra' of 

 the neck, which were first brought back by Darwin from 

 the superficial deposits of Patagonia. In its general form 

 the macranchenia, of which a complete skeleton from the 

 Pampean formation preserved in the museum at Buenos 

 Ayres is represented in the accompanying figure (3), 



the nostrils is carried to a still greater degree. That a 

 land mammal with its nostrils situated in this unusual 

 position could not have managed to exist without a trunk 

 is pretty evident, and we may therefore conclude that the 

 macrauchenia was so furnished ; while from its long 

 slender neck and limbs we may fiu-ther infer that it was 



Fig. 3. — Skoietou of the Macraiiclicuia. About one-fifteenth natural size. (After Bravaril.) 



somewhat recalls a camel ; and it is a curious circumstance 

 that in common with that animal and its allies it differs 

 from all other ungulates, with the exception of certain 

 kindred Ai-gentine forms, in that the vertebral artery of 

 the neck pierces the sides of the vertebrae to take a course 

 within the spinal canal, instead of passing merely through 

 a loop of bone on the exterior. This remarkable resem- 

 blance is not, however, indicative of any afliuity between 

 the two animals, since if we look at the feet of the 

 macrauchenia we shall find that they are of the odd-toed 

 type, and are each furnished with three digits. Moreover, 

 the huckle-bone has the pulley-like upper surface 

 characterizing the odd-toed migulates ; while as the 

 teeth approximate to those of the latter, we might be 

 inclined to place the creature in that group. The 

 wrist and ankle joints are, however, formed on the 

 linear plan, and exhibit certain other departures from 

 the odd-toed type, and it is therefore evident that the 

 macrauchenia and its allies constitute a third subordinal 

 group of exiinct ungulates peculiar to South America. 

 Although it is by its foot-structure that the macrauchenia 

 is thus separated from all other members of the order, its 

 most remarkable peculiarity is to be found in the structure 

 of its skull. In an ordinary well-regulated mammal the 

 aperture of the nose is situated quite at the anterior 

 extremity of the skull. In the macrauchenia, however, 

 the said aperture is an egg-shaped vacuity in the forehead, 

 placed almost between the eyes. Some approximation to 

 this remarkable arrangement is presented by the living 

 tapirs, but it is more nearly paralleled by the elephants, and 

 still more closely by the aquatic dugong, whUe among 

 whales the backwardation (if we may coin a word) of 



an inhabitant of open plains or thin forest, and was not a 

 frequenter of marshes and swamps." It may be added that 

 in its uninterrupted and even series of teeth the macrau- 

 chenia differs from all existing mammals save man, and 

 agrees with its distant cousin the homalodontothere. 



From its large size, the peculiar position of its nostrils, 

 and the characters of its molar teeth, the zoologist is at 

 once led to infer that the macrauchenia is a highly 

 specialized creature ; and it is of the greatest interest to 

 find that this inference is converted into a certainty by 

 the discovery of certain kindred forms in the older forma- 

 tions of the Parana and Patagonia, which are evidently 

 the ancestral types from which the Pampean genus has 

 originated. All these creatures were of relatively small 

 size, with their molar teeth more closely resembling those 

 of the odd-toed ungulates, and they show a gradual transi- 

 tion in regard to the position of the nostrils from the type 

 of the macrauchenia to the ordinary form. The evolution 

 of such an extraordinary creature as the one under con- 

 sideration is, therefore, fully explained, although we have 

 yet to learn the special reason for the peculiar position of 

 its nostrils and the development of a trunk. 



More or less intimately allied to the ancestors of the 

 macrauchenia were certain contemporaneous ungulates 

 from Patagonia, of which the largest did not exceed a 

 tapir in size. With molar teeth so like those of the odd- 

 toed ungulates from the Paris basin, described by Cuvier 

 as Pahi'othimum, these Patagonian ungulates differed from 

 the macrauchenia in having the dental series reduced in 

 number and interrupted by gaps. Their most remarkable 

 pecuUarity is, however, to be found in the structure of 

 their feet, which, in some forms at least, resembled those 



