THERE are 140 species of the cactus family in the United States, all of which are embraced in five genera, or practically in four genera, as the fifth contains only one species. The four principal genera are as fol-lows : cereus, 34 species; echinocactus, 23 species; mamillaria, 30 speoies; opuntia, 52 species. It is difficult to describe the differences between these genera in popular language. There are but two or three species growing east of the Mississippi river. About half a dozen species are spread over the Great Plains between the Missouri river and the Rocky Mountains, a few of them reaching into Montana and Idaho. In Utah and Nevada many additional species occur, mostly species which are also common farther south. But in the desert region of the southwest, extending from western Texas, through New Mexico, Arizona and southern California, the species become very numerous, and form a characteristic feature of the vegetation. The distribution of the species is by no means uniform, however. Some species are spread over nearly the whole field, while others are more or less restricted.

We can here only take notice of such species as would either on account of their abundant and constant appearance, or from their peculiar and striking characters, attract the attention of the traveler.

The species of the genus mamillaria are mostly small roundish pulpy bodies, seldom more than three or four inches in height or diameter, studded with tubercles which are densely covered with spines. Most of the species of the genus echinocactus are also low, ovate or cylindrical-ovate bodies, marked by more or less prominent ribs running from base to apex, on which are situated the tubercles and spines. The same general statement will apply to many of the species of the genus cereus, especially of those inhabiting New Mexico and Texas. In Arizona and southern California some of this genus have tall, columnar trunks.

The genus opuntia, commonly known as prickly pear, has some species with flattened, and some with cylindrical, branching joints. Some of the species are low or spreading on the ground, and others assume a branching or bushy form.

A favorite region for cactus plants is in western and southern Texas ; especially do they abound on the hills and bluffs of the Rio Grande river, extending up the country of the Pecos into New Mexico and over the region formerly known as the Staked Plains.

In southern and southwestern Texas, in the countries bordering the Rio Grande, several species of the flat-jointed opuntias, particularly Opuntia Engelmanni and Opuntia Lindheinmeri, occur. These grow from four to six feet high, extending over large tracts of country and sometimes forming thickets which it is difficult to pass through.

Within a few years the cattle raisers of this region have found means of utilizing these plants for the feeding of cattle. Ordinaratly. cattle do not touch these plants, but when driven by hunger they attack them, notwithstanding the cruel spines or needles with which they are armed. It is found that by burning the spines so as to destroy the points they are rendered comparatively harmless. Some feeders use a cutting box prepared for the purpose, and by holding the cactus joints in a proper direction cut off the spines with rapidity and also cut the joints into pieces to feed to the cattle. They frequently mix them with meal or bran or cottonseed meal, and in this manner fed to cattle they are said to be of great value. Sheep and hogs are also fed upon them. It is also stated that the young joints of the cactus are used in early spring by the Mexican population of western Texas as food. They are cut into small pieces, mixed with flour in a batter, and fried. This dish is said to be as palatable as egg-plant.

The common name of these large opuntias among the Mexicans is Nopal, although that name belongs more properly to a similar Mexican species (Opuntia Ficus-Indica, or Indian Fig, Fig. R.) which is cultivated for the sake of its pulpy fruits, which are highly esteemed and sold in all the markets. Another notable and related species is cultivated for hedges and is naturalized about the old Missions in southern California. It is called Tuna (Fig. T), and grows ten to fifteen feet high. Its fruit is large, well flavored and edible.

A western variety (var. occidentalis) of the Opuntia Engelmanni occurs on the western slopes of the mountains in southern California. This has stout woody stems, with innumerable branches, amounting to sometimes over 100 joints. It was found northeast of San Diego at elevations of 1,000 to 2,000 feet, in immense patches, often as large as half an acre. Dr. Bigelow also found it 40 miles east of Los Angeles in extensive areas.

Another species of similar habit, but somewhat smaller, occurs throughout Arizona and the desert region of California. It is the Opuntia angustata (Fig. PP.) It grows in large patches of eight to ten feet in extent, mostly prostrate, but with some of the branches standing three or four feet high. The joints are six to ten inches long, obovate, gradually narrowed to the base, and with more numerous fascicles of spines than in O. Engelmanni. The pulpy fruit is perhaps, about 1½ inches long, and x inch in diameter.

Some of the opuntias have cylindrical joints or branches. The one most widely diffused is probably Opuntia arborescens, or "tree opuntia." This comes into view in northeastern New Mexico, where it may be seen by travelers, along the line of the railroad, a strange naked looking, erect, stiff object three to six feet high with half a dozen rigid branches standing out at all angles, and displaying their savage spines. In the hills about Santa Fe they are abundant. From here they extend westward into Arizona and southward on rocky ridges and barren mesas into Texas and southern New Mexico.

Of the cylindrical branched opuntias there are in Arizona two or three species (particularly O. Whipplei and O. Bigelovii) which attain a height of ten or twelve feet, with an erect woody stem and many spreading branches. In O. Whipplei the young joints are four to twelve inches long, and one-half to three-fourths of an inch thick. This curious plant is shown in Fig. P. Several smaller species attain a height of four to six feet.

These opuntias are very conspicuous in the valleys of the Gila and Bill Williams mountains of Arizona, and both men and animals give them a wide berth on account of the innumerable forbidding spines with which they are covered. It would seem as if vegetable life in this region is so precarious and exposed to so many dangers that nature finds it necessary to protect the plants by an armor of the most forbidding and offensive kind.

The genus echinocactus, including the barrel cactuses, is perhaps the most formidable of all in its defensive armor. Here the spines, or a part of them, are generally flattened and thickened at the base, and gradually narrowed to a sharp point like a shoemaker's awl. They are sometimes three or four inches long and very stiff, so that they are capable of inflicting serious wounds. In some species these spines are hooked at the point, and catch hold of the clothing or any object coming in contact with them.

One of the largest of this genus is Echinocactus Wisle-zenii. It is roundish-ovate or oblong in form, growing under favorable circumstances 3 to 5 or more feet high, and 1 or 2 feet in diameter. It has from 21 to 25 ribs running from apex to base, which are covered with clusters of spines at frequent intervals. Notwithstanding its formidable appearance, the inhabitants of the country have learned that it contains an abundant watery pulp, to which they often resort for the quenching of thirst. This pulp is also sometimes prepared like citron into a pleasant confection. Fig. D. represents a good specimen of Echinocactus Emotyi, a species found on the Lower Colorado. It attains a height of three feet, and a diameter half to two-thirds as great.

The flowers are clustered near the top. They are about three inches long, dark brown purple outside, and red and yellow inside.

But by far the most striking objects of the cactus family are the giant trees of the genus cereus, of which Cereus giganteus is the chief (Fig. A), Half a dozen of these have been transplanted to the yard attached to the railroad station at Tucson, Arizona, where they can be seen by travelers. But farther west they can be seen from the cars in many places. On the slopes and at the base of hills and rocky steeps they frequently attain a height of 50 or 60 feet. They are sometimes un-branched, appearing like massive cylindrical columns, but often they have two or three or even as many as nine branches, which immediately after leaving the trunk turn upward and grow parallel with the main stem, presenting the appearance of an immense candelabrum. The trunk is often 2 feet in diameter. They are not found above the altitude of 3,000 feet. They seem to thrive best in the most desolate and arid localities, on the slopes of valleys and on the desert plateaus. These trees, so unlike anything familiar to northern travelers, are the most striking objects of this great desert region. I surveyed a group of these giants with emotions of wonder and admiration.

In the vicinity were seen many young plants growing under the shade of the green-barked acacia, which acts as a nurse plant in protecting the young cereus in its early stage of growth.

The center of the trunk is composed of a juicy pith, four to six inches in diameter; surrounding that is a cylindrical frame work of woody bands, tough and elastic, and externally is a fleshy or pulpy coating which communicates with the pith through openings in the wood. The flowers are borne near the summit, and are succeeded by a roundish fleshy fruit, of the consistency of a fig, and of a sweet but rather insipid taste. This fruit the Mexicans call pitaya. It is dislodged from the tree by means of a long light pole with a fork at the end. Two other species of tree cactus occur in the neighboring province of Sonora, Mexico, and another or two in the peninsula of California, and in South America there are several others.

Washington. George Vasey.