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But many among the otherwise useful and ornamental plants of Trans-Pecos Texas are provided with fearful spines and thorns; many of them, for instance, the lecheguilla, the cacti of the opuntia family, the tornillo, the allthorn, catclaw, etc., are so numerous, and in many localities so close together, they obstruct the passage of man and beast; but their usefulness overbalances their objectionable qualities, particularly in this nearly uninhabited part of the State.

The most dreaded weed, however, is the loco or crazyweed (Astragalus molissima). The symptoms of a disease of horses, claimed to be the result of this plant, are peculiar. The most gentle horses get wild and uncontrollable. They lose the appetite, stand dull and motionless for hours, but get highly excited when approached, even by their master. In short, they show signs of mad insanity, together with bodily disease. Full recovery is scarcely heard of, and it is claimed that the animals, if recovered, grasp every opportunity to eat again the poisonous plant. I have seen many instances of "locoed horses," but I would not like to decide if the loco weed or something else caused the disease.

The United States Agricultural Department expressed some years ago the opinion that this plant does not contain any poisonous principle, but that the velvety covering of the leaves might, perhaps, irritate the stomach of the horses to such a degree as to cause the disease. But the effect on horses, if the disease is the result of loco eating, reminds one more of the effect of narcotic poisons than of the effect of an irritation of the stomach, and the inhabitants of localities where the plant grows believe strictly in its poisonous character. The Mexicans also assert that it causes insanity in human beings. No remedy is known against the loco disease.

STRATIFIED ROCKS.

The study of the stratified rocks of Trans-Pecos Texas is as complicated as that of the eruptive ones.

The Cretaceous strata of the western portion of that country are detached fragments, the remnants of deposits, the original boundaries of which can only be determined by detailed local study, though, to generalize, it may be said that the cliffs of Carboniferous limestones seem to have been the shorelines of the Cretaceous sea.

In the foothills of the Quitman mountains the Cretaceous limestone strata rest directly on eruptive rocks, in the Sierra Blanco group, where they rest on a microcrystalline granite, which can not very well be regarded a metamorphism of the Trinity sandstone. In some places eruptive rock appears protrusive and extrusive through Cretaceous limestone, tilting and disturbing the strata, and demonstrates the activity of eruptive