q6 The American Geologist. August, i90o 
ing. I could not have desired anything more agreeable nor sur- 
prising than this discovery of our lowest Eocene 500 miles south of 
where now known! and in fall confirmation of my theory published 
last winter that the fauna of Fort Bridger beds came from the south! 
Thee need not mention this for a while, for reasons which I will pres- 
ently mention." * * "The party had to wait at San Juan (which is 
an Indian Pueblo town), so Mr. Shedd and myself left for an explora- 
tion of the bad lands on the w. side of the Rio Grande, opposite San 
Ildefonso, and of the Jemez mountains. This we did, camping two 
nights, once in the pine forest on the foot hills of the mountains. We 
climbed the first range, say 9,000 ft. high, and had a most gloripus view 
of the valley of the Rio Grande, with its bad lands, and the Rocky 
mountains on the east, rising 1,000 ft. We found fossils. Mastodon, 
Rhinoceros, camel. Merychyus, and a fine vulture. Yesterday Mr. 
Yarrow and self fished in the lagoons of the Rio Grande and caught 
ten species, many new, and two new genera." 
"Santa Fe, August 29, 1874. Dear Father" * * "For over a 
week we have been investigating the bad lands near San Ildefonso. 
and only find them moderately rich in fossils of Pliocene age. We 
have some 25 species of Vertebrata, including three dogs, a weasel, 
a mouse, a beaver, and a gopher; two horses, a rhinoceros, one or 
two species of Mastodon, three camels, and three species of Cosoryx, 
a genus intermediate between antelope and deer. The origin of the 
curious phenomenon of the shedding of their horns and redevelop- 
ment periodically by the deer has always been a puzzle to evolution- 
ists, but these curious ruminants, I think, furnish the clew. I have 
some twenty-two specimens, mostly the horns of only one side, and 
about half of tl^ese have a burr at the base like a deer, and the other 
half are solid and smooth. I find that those with burrs have all been 
broken, and reunited or "ankylosed." Some of the antlers (the horns 
of 2 sp. are branched), also produce a burr where broken. I believe 
deer descended from permanently horned ruminants, which frequently 
broke their horns in fighting in the spring rutting season, and that 
the effort to repair the break became periodical, and growth was 
thus directed to this region. 
This is a very peculiar country. The valley of the Rio Grande 
varies in consequence of three conditions. First, where the great 
surface bed of basalt is unbroken, it is level and barren, with grass 
and brush, and the surface is level, the river running in a deep cafion; 
second, where this bed is broken up, the underlying pliocene soft 
sand leaves the country in dry sand hills, with scattered cedars; or, 
third, where there is water, in grassy and rich valleys among the foot 
hills of the mountains. Such a valley contains Placita. It is a beauti- 
ftil place, and displays rocks of four periods, in the latest of which I 
found remains of Elephas primigenius. The bed is thus postpliocene. 
and not the pliocene I looked for. There are but few species of trees, 
only pine, cedar, and cotton wood, but flowering plants with large 
arrow-shaped leaves run over the ground and various species of 
