236 THE INTERNATIONAL MONTHLY. 
to progress in the same direction. Especially marked is the 
increase of stature, which much exceeds that of the Uinta type 
and, in the larger White River species, equals that of a sheep. 
The canine teeth are beginning to enlarge and show signs of 
assuming the formidable, lacerating shape of the modern camels, 
while the growth of the jaws begins to produce gaps in the dental 
series, tending to isolate the canines. The molar teeth have 
much longer crowns than in any of the preceding genera, taking 
the first step toward the development of the prismatic form. The 
skull is very llama-like in appearance and the orbits are com- 
pletely enclosed in bone ; the neck is much elongated and its 
vertebrae* have acquired the extremely peculiar and characteristic 
shape found in the modern camels and llamas. The limbs are 
relatively much longer than in the Uinta genus and the external 
forearm and leg bones (ulna and fibula) are completely reduced. 
The fore leg has increased proportionately more in length than the 
hind, so that both are nearly equal, while in the Uinta genus the 
hind limb was considerably longer. The lateral digits are now 
almost completely gone and are represented only by very small 
nodules of bone; but the median pair are still separate from each 
other, not coalescing to form a " cannon bone." The hoofs are 
long, slender, and pointed, and evidently bore the full weight of 
the animal, which shows that the curious pad or cushion upon 
which the foot rests in the llama and camel had not yet appeared. 
The John Day genus (Protomeryx) is very similar to its White 
River predecessor, but continues to advance along the same lines. 
In the Loup Fork type (Procamelus) the transformation is almost 
complete ; the genus has several species, some of which appear to 
be ancestral to the true camels, others to the llamas, while others, 
again, are peculiar and have no existing descendants. These ani- 
mals are much larger than their ancestors of the John Day, and 
have longer necks and limbs ; the upper incisor teeth (except the 
external one on each side) are beginning to diminish and dis- 
appear, and the grinding teeth have elongate, prismatic crowns. 
In the feet, both fore and hind, the long bones of the two remain- 
ing digits coalesce to form cannon bones, and the hoofs are 
