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The principal fossils seen to-day are Arcopagia Texana, Gryphœa Pitcheri, Janira quadricostata, Cardium multistriatum, Ammonites acuto-carinatus, and Pterodonta (Eulima) subfusiformis.

Late in the day we came to Live Oak Creek, a beautiful stream of clear water, flowing over a rough, rocky bed. The temperature of this stream was found to be 70 degrees F.

The soil, during the greater portion of the day's march, was barren, being composed principally of disintegrated limestone; but in the vicinity of Live Oak Creek it is moderately fertile, and supports a sparse growth of oak trees.

Distance, 11 miles.

May 11.-Beyond Live Oak Creek our route lay over a broken, rocky region, characterized on all sides by rough hills and cliffs of thin-bedded Cretaceous Limestone, some of which attain a height of more than five hundred feet.

As we progressed through the canyon it widened rapidly, and finally opened into the broad valley of the Rio Pecos, which here pursues a tortuous course between rough hills and picturesque cliffs from four to six hundred feet high.

The water of this stream is of a deep red color, and contains some muriate of sodium. Its average width is about seventy-five feet. Temperature 70 degrees F.

The valley possesses a red clayey soil, which appears to be moderately fertile.

Near the bed of the river I observed a layer, a few feet thick, of coarse breccia, made up of fragments of limestone, loosely cemented with a calcareo-ferruginous paste.

Distance, 7¼ miles.