says "that it [Acacia] forms a shelter for the propagation of the Cereus giganteus of that region. Every young Cereus is protected and fostered by this tree until the cactus attains the size and hardihood that enables it to withstand the war of elements waged against it, when it ungraciously spurns its protector, ultimately destroying it, as we saw in numerous instances on our journey."

That geological and climatic influences and effects modify and in time alter the flora of a district is perceptible in the salt marshes. Here the lower forms of vegetation flourish in luxuriance, especially the Chenopodiaceae, in which the higher types seem unable to exist on account of the strongly alkaline soil, and even in waters strongly impregnated with salt, forms exist which retain these places in spite of the force brought to bear upon them from the invading species which perish not from a "mutual repulsion and subjection," but from the alkalinity of the soil itself.

Mr. Lester F. Ward proposes "what might be called the law of mutual repulsion, by which every individual, to the extent of its influence, repels the approach of every other and seeks the sole possession and enjoyment of the inorganic conditions surrounding it; this mutual repulsion results at length in a statical condition which is always brought about through the action of the vital forces themselves, and which, as soon as reached, determines absolutely the exact place and degree of development of each species and each individual."

This is at present not the case in the salt marshes, but, when an accumulation of organic and silicious matter is the result, through the decomposition of the plants and the dust from surrounding sources, these lower types lose their predominance, and higher types replace them. This will ultimately be the result, as there is no aqueous precipitation, and the constant evaporation from the marshes will leave them nothing but alkaline deserts.

Upon the foot-hills in the upper portion of Nevada different species of plants occupy distinct patches, but it is apparent that there are changes going on, and that in time some will be destroyed, giving place for hardier varieties. Mr. Ward further says, "Each species is the perpetual and inexorable antagonist of every other. The struggle' is not alone for existence,' it is also for space. But the first principle, as in the rest of nature, is force. Each one encroaches with all the power of

vegetal growth upon its neighbors." Where an area of vegetation has not been disturbed by mechanical or agricultural causes, the species and genera growing thereon are to all appearances occupying their limit of growth and local distribution, as over various valleys and low elevations in Northern Nevada. "But let these statical conditions be once changed, . . . . and this equilibrium is immediately disturbed. The chained forces are set free; a general swarming begins; some individuals are destroyed, others are liberated; each pushes its advantage to the utmost, and all move forward in the direction of least resistance, till at length they again mutually neutralize each other, and again come under new conditions and modified forms, into the former state of quiescence." 1

There has been great difficulty experienced in some of the fertile valleys of Nevada and California in attempting to prevent the rapid encroachment of native plants upon partially cultivated and irrigated patches of soil. They are stronger in vegetal power, and in a short time depauperate and stunt the introduced cereals and garden vegetables.

These vegetal "struggles for space and existence" are stronger and the results more perceptible in the tropics than elsewhere; rising in altitude with the superlying belts of vegetation, they decrease until the region beyond the timber-line is reached, in a similar manner as when we proceed towards either pole in almost a fixed proportion to the latitude. This is caused by a variety of influences, prominent amongst which are

(1.) The presence of saline matter to such an extent as to cause the destruction of any but the lower types of vegetable life, Chenopodiaceae.

(2.) In the sub-alpine belt or latitudes, where the Conifero predominate and where there is a corresponding temperature unfavorable to other types generally, and

(3.) Beyond the timber-line or at extremely high latitudes, where the superincumbent mass of snow in winter and the extremely short temperate season prevent the growth of almost anything save lichens and mosses.

1 Mr. L. F. Ward, Popular Science Monthly, October, 1876.

7

IN

ABORIGINAL SHELL MONEY.

BY ROBERT E. C. STEARNS.

N several articles heretofore published,' I have written on the use of various species of shells for the purposes of money by the aborigines of North America, and have also briefly referred to the use of the same class of material for similar purposes in Africa and India, and the antiquity of shell money in the latter country.

Since the date of my last paper additional data have been acquired, which are worthy of note as they relate to certain West American species of mollusks not before enumerated, the shells of which have been and to some extent are still used for money by some of the Indian tribes in California.

The discovery of a species of Olivella (O. biplicata Sby.) in ancient graves on San Miguel Island (one of a cluster of islands thirty miles westerly) off the southerly coast of this State was referred to in a previous paper. I have since examined specimens of the same species, found by Mr. C. D. Voy in a burial mound near Vallejo, in Solano County, in the year 1872, now in the museum of the University of California, which also contains much rare and interesting prehistoric material collected by the same person in various parts of the State. Of this species about two hundred specimens were obtained from the Vallejo mound, as well as human remains and numerous aboriginal relics, such as stone pipes, bone whistles, and arrowheads, also another form of shell money and ornament described further on.

(FIG. 62.) OLIVELLA BIPLICATA SBY.

In all of the Olivellas from the Vallejo mound, the upper part of the spire or the apex of each shell has been ground off in the same manner as in the San Miguel Island specimens,2 and it is presumed that they were formerly strung and worn as a necklace, an ornament for which these shells are still used by some of the interior Indians of Central California, as I have been informed by Mr. Stephen Powers, a most excellent authority. He says that this form is now used for personal adornment by the Bear River Indians, and is by them called "colcol." Referring to the shells he writes, "They are strung double, that is, two strings of them

1 American Naturalist, March, 1869; Overland Monthly, April, 1873; Proceedings of the California Academy of Sciences, July, 1873.

2 Collected by Mr. W. G. W. Harford.

are tied together between each two shells, so that the shells are mouth to mouth. But even this double string is lightly esteemed, being worth only one dollar a yard. It is little used for money, being rarely seen at all, and is worn chiefly by the women in dances as a cheap jewelry."

(FIG. 63.) COLCOL.

The specimens kindly sent to me by Mr. Powers are of the white variety, which are much less abundant than those of the usual bluish tinge; neither are these nor any of the grave specimens above a medium size, for this species frequently attains a length of an inch and a quarter, as may be seen in Figure 62. The Vallejo mound specimens average only half an inch, which fact suggests that the smaller size may have been more highly valued. It will be observed that the Olivellas, or colcol, have been found in ancient graves on San Miguel Island associated with human remains and prehistoric implements, also by Mr. Voy in Solano County, and Mr. Yates in a recent article reports their occurrence in the mounds of Contra Costa and Alameda counties.

By reference to a map of California it will be seen that these last localities are widely separated from the first named, and it implies not only the general use of this species of shell by the maritime tribes, but also a line of intercourse and a system of traffic between the coast tribes and those of the interior, as suggested in a previous paper, and through which the colcol finally came to be used by the Indians of the central part of the State.

In my first paper,1 alluding to the use of Saxidomus gracilis, a common bivalve on the coast of Sonoma County, I expressed surprise that the equally common and far more beautiful shells of Haliotis rufescens had not attracted the attention of the aborigines, and been utilized by them for money and personal decoration. It will be seen, however, that the beauty of these has not escaped the eye of the savage, but that they have been used both for money and for personal decoration, and been fashioned into a variety of shapes for the latter purpose, the prototypes of the "abalone jewelry" so popular with the "pale-faces" of to-day.

From the Vallejo mound Mr. Voy obtained various pieces of Haliotis, or abalone, as the Californians call it, which is the aulon or aulone of the Spanish, and the uhllo of the Indians. In reference to the Indian name Mr. Powers writes: "Your conjecture

1 American Naturalist, March, 1869.

that the word uhllo is corrupted from the Spanish aulon is probable, although the Indians accent the first syllable, giving it a sound difficult for us to imitate, somewhere between uh and the German ö."

The accompanying illustrations represent the specimens taken from the Vallejo mound in the. year 1872, with which, as before stated, were found. human remains and numerous aboriginal relics. They form a part of the Voy collection presented (FIG. 64.) HALIOTIS to the University of California by Mr. D. O. Mills, OR ABALONE. of San Francisco.

These ornaments and this money, if we may consider the circular pieces as the latter, are all made from the same species of Haliotis (H. rufescens Swainson), the common red-backed abalone of the coast, which has a range of nearly the entire shore line of the State; and a large species which sometimes attains a length of eleven inches.

In Figure 2 of Plate II. we have an approximately circular disk; Figure 1 in the same plate may have been nearly the shape of 2, and have become partially disintegrated and scaled or flaked off, since it was buried, through oxidation and decay. The dark patches on these figures represent the red exterior of the shell from which they were made, and which still remains on the specimens. Figure 3 is well worked out, a nearly perfect circle with the edges neatly serrated or toothed, as if done with a sharp piece of obsidian, while Figure 4, though without apparent design, has been rubbed or rounded so as to make the edges smooth, as have also the pieces figured in 1 and 2, and the holes have been carefully perforated. Figure 4 shows the mark where a hole was started and not completed, probably from its being too near the edge.

Over a dozen of these disk-shaped pieces, including those figured, were found by Mr. Voy, and Mr. Yates also records approximately similar forms of smaller size, though he does not state the species of Haliotis from which his specimens were made. Mr. Henry Edwards, the entomologist, has also obtained this abalone money from the kitchen-middens of Marin County, near Saucelito.

Mr. Powers, referring to the use of Haliotis, says, "The uhllo pieces are of a uniform size on the same string; they do not mix them. The dollar pieces (Plate II., Figure 5) are generally about one and one quarter inches long and an inch wide; the smaller about as long but narrower ; . . . a couple of fragments