FROM QUATEENABY DEPOSITS IN THE VALLEY OF MEXICO. 73 
which makes a step toward the Cameline modification. The diapophyses are imperfo- 
rate in the seventh cervical of Palauchenia : in that vertebra of the Dromedary’s skeleton 
in the British Museum (673 a) the vertebral artery traverses lengthwise the base of each 
diapophysis; but in a specimen in the College of Surgeons’ Museum (No. 3455) the 
vertebral arteries do not perforate any part of the vertebra. In both, as in the skeletons 
of the Camels, Dromedaries, and Lamas at the Jardin des Plantes, where I first (in 1831) 
observed the fact, the vertebral arteries enter the neural canal of the sixth cervical and 
perforate the neurapophyses, emerging forward at the inner side of the base of each 
prezygapophysis. In the seventh cervical vertebra of a Lama’s skeleton in the British 
Museum, as in the corresponding one of that in the Surgeons’ Museum (Catalogue of 
the Osteology, 4to, 1853, p. 578, No. 3487), the right diapophysis is perforated by the 
vertebral artery, the left one not. 
In size and general shape the cervical vertebrae of Palauchenia recall those of Macrau- 
chenia , but detailed comparison brings out greater differences than any of those above 
noted in Auchenia and Camelus. 
The vertebra dentataof Palauchenia differs from that of Macrauclienia* in being more 
slender, in having a lower neural spine, in the shorter diapophvses, and in the non-bifur- 
cation posteriorly of the hypapophysis. 
The third and fourth cervicals of Palauchenia differ from those of Macrauclienia in 
the longer, narrower, but thicker and more tuberous pleurapophyses, in the convexity 
of the anterior surface of the centrum ; and this latter character distinguishes the suc- 
ceeding cervicals from the corresponding vertebrae of Macrauclienia , in which that surface 
is less convex, being nearly flat at the middle part. 
Thus, the general result of the comparison of characters of the vertebrae of the neck 
concurs with that of the dental characters in demonstrating the former existence in 
America of a Cameline Buminant as large as the largest variety of living Camel or Dro- 
medary, with closer affinities to the Lamas and Vicugnas, yet with such departures from 
the dental and osteological characters of Auchenia as seem to justify their indication by 
the generic or subgeneric term Palauchenia, here proposed for such extinct form of 
American Cameline quadruped. 
* Plate 6 & 7, Fossil Mammalia of the Voyage of the ‘ Beagle,’ 4to, 1860. 
MDCCCLXX. 
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