in their native state and in all stages of development, it can hardly be expected that any one should know beforehand what constitutes the specific characters in these plants. I have tried to unite the forms which seemed to justify such a proceeding (see, e. g. O. Rafinesquii, here made to comprise quite a suite of forms as subspecies). Still it may be thought that a greater reduction was yet desirable; but with our present data this would involve great danger of jumbling heterogeneous materials together. Nos. 5 and 7 (of which latter neither flower nor fruit is known) can perhaps be united; also 9 and 10, 11 and 12, 13 and 14, 16 and 17, 19 and 20, 22 - 24, 25 – 28, 29 and 30, 31-33, 35 - 37, 38-40, and 48 and 49,- leaving 31 types, 29 of which are indigenous to our territory, and two cultivated.

Geography of the Cactus Region of the United States.

The localities where our Cacti grow are so little known to those who have not made the geography of the West a particular study, or are familiar with the publications of our Western explorers, that it seems necessary to add a few explanatory remarks.

Texas, as at present organized, is bounded southeasterly by the Gulf of Mexico, into which the following rivers mentioned in the foregoing pages empty, following the order from east to west: the Brazos, the Colorado with the Llano, the Guadalupe with the Pierdenales and San Antonio, the Nueces, and the Rio Grande. The latter forms the southern and southwestern boundary as high up as El Paso. On it are the towns of Matamoras (not far from its mouth), Mier, Laredo; and higher up, Presidio del Rio Grande; then Fort Duncan or Eagle Pass (southwest of which is Santa Rosa, in the State of Coahuila); next comes the mouth of the San Pedro or Devil's River (a small river or rather torrent running southward), and not far from it the mouth of the Pecos or Puerco, which rises at the north-northwest in the upper parts of New Mexico. Between the mouth of the Pecos and El Paso we notice only Presidio del Norte, San Elizario, and a "cañon" below the latter. The valley of the Limpio, a little more to the northward between the Pecos and El Paso, is a remarkable locality; probably because there porphyritic rocks take the place of the cretaceous formation of the more eastern districts.

Chihuahua is the well-known capital of the Mexican State of the same name, south of El Paso.

The Canadian River is a southern tributary of the Arkansas, running eastwardly very nearly under the 35th degree of latitude, and bounding on the north the elevated plains known as the Llano Estacado, in the northwestern parts of Texas and the adjoining regions of New Mexico.

The Upper Rio Grande runs through New Mexico from north to south; the capital, Santa Fé, is not far from the river, in lat. 35°; and the town of Albuquerque is a little below. Doñana is a small place on the river, above El Paso. El Paso itself, where the Rio Grande breaks through the mountain ranges, changing its heretofore southern to a southeastern course, is the central point of our Cactus region, partly from its geographical position, and partly because many of our explorers have made it the centre of their operations.

The present southwestern boundary of the United States runs from El Paso irregularly westward through the former Mexican State of Sonora, to the Colorado "of the West," or "of California," which comes from the South Pass in the Rocky Mountains, and runs southwestward and southwardly. Its principal tributaries rise in the east ; those most important to us are the Little Colorado or Colorado Chiquito, under the 35th and 36th degree of latitude; Bill Williams's Fork, or Williams's River, as it is lately styled, further south; and in lat. 33° the Gila River, which rises near the "Coppermines," northwest of El Paso.

Proceeding from Santa Fé westward, we find the Indian town of Zuni, on the head-waters of the Little Colorado; then the San Francisco mountains; the Cactus Pass, at the head of Williams's River, and this stream itself. All this territory is at present included in the political organization of New Mexico, though uninhabited by whites.

West of the Colorado, in lat. 35°, is the Mojave or Mohave River, rising in the Sierra Nevada near the Cajon Pass; lower down, opposite the mouth of the Gila, the country is a sandy desert extending westward nearly to San Felipe, on the eastern slope of the California mountains in the same latitude. On the western sea-coast the town of San Diego is the only interesting point for the plants under review.

Geographical Distribution of the Cactacea in the Territory of the United States.

As to the geographical distribution of the Cactacea, our territory may properly be divided into eight regions, viz. :—

1. THE ATLANTIC REGION; which has only a single Opuntia, and that peculiar to it. Along the Southern coast some West Indian species may yet be expected.

2. THE MISSISSIPPI REGION, including the Western States, produces another Opuntia, which, in different distinct forms, extends into the 3d, 4th, and 5th regions.

3. THE MISSOURI REGION; namely, the Northwestern or Upper Missouri Territory to the Rocky Mountains. It furnishes

Two Mamillaria of the subgenus Coryphantha, both extending into the 4th and 5th region; and

Three Opuntia, one of which only is peculiar.

4. THE TEXAN REGION; namely, the eastern and inhabited parts of Texas, westward to the San Pedro, and northward including the territory south of the Arkansas River. This region produces

Five Mamillaria, two of them peculiar to this district;

Three Echinocacti, none of which are found in any other of our regions; *

Six Cerei (five Echinocerei and one Eucereus), all of them peculiar to this district; and

Six Opuntia, of which only three are restricted to it; among them is only a single cylindric Opuntia.

This region contains therefore altogether twenty species, fourteen of which are peculiar to it.

5. THE NEW-MEXICAN REGION; namely, Western, uninhabited, mountainous Texas, and Eastern New Mexico to the eastern headwaters of the Colorado of California. This region is our richest Cactus district. It has furnished sixty-five species, fifty-five of which are peculiar to it, viz. :

Nineteen Mamillaria (eight Eumamillaria, ten Coryphantha, and one Anhalonium), of which sixteen are peculiar;

Nine Echinocacti, all of them belonging to this district only; Sixteen Cerei (fifteen Echinocerei, fourteen of which are peculiar, and one Eucereus, common also to other regions); and

Twenty-two Opuntia; of these twelve are flat-jointed, four clavate, and five cylindrical ones: seventeen of these species are peculiar. 6. THE GILA REGION, comprising the whole valley of the Colorado

Always excepting Mexico itself, south of the Rio Grande, into which many, if not most, of our species extend.

south of lat. 36°, and the country of the Gila, its large southern tributary. This has thus far furnished thirty-six Cactaceae, viz. :—

Five Mamillaria, three of them peculiar species;

Six Echinocacti, none of them found elsewhere;

Seven Cerei, representatives of each of our four subgenera, and five of them peculiar ;

Eighteen Opuntia, of which six (all peculiar) belong to the Platopuntia, two to the clavate and ten to the cylindric Cylindropuntia ; one of the former and nine of the latter peculiar.

7. THE CALIFORNIAN REGION, namely, California west of the Sierra Nevada, and comprising the southwestern part of the present State of California, produces six Cactaceæ, five of which are peculiar. They are,

One Mamillaria;

One Echinocactus;

One Cereus of the section Eucereus; and

Three Opuntia; one of them a Platopuntia, probably only a form of a more eastern species, and two peculiar Cylindropuntiæ.

8. THE NORTHWESTERN REGION, comprising the northern parts of the State of California, the Territories of Utah, Oregon, and Washington. This region has so far furnished only a single Opuntia (from Eastern Oregon), common also to the Missouri Region. — Mr. Geyer, in his account of his expedition to Oregon in 1843, mentions two Mamillaria and a "Melocactus" (?), which latter he has not seen himself, nor are there any known specimens in existence.

CORRECTIONS AND ADDITIONS.

P. 267. Mamillaria scolymoides has been collected by Mr. Wright, on the Pecos, in Western Texas.

P. 273. 9th line from top, dele "1" after "fuscatis."

P. 278. 5th line from top, for "parallelæ" read "contrariæ.”

P. 286.

Cereus Berlandieri is very near C. pentalophus, DC., but Prince Salm, who has cultivated both side by side, considers them well distinguished.

P. 300. Opuntia Missouriensis has been sent from Clear Water, on the Kooskooskie, in Oregon, by the Rev. Mr. Spalding.

Four hundred and twenty-ninth meeting.

August 13, 1856.-STATED MEETING.

The PRESIDENT in the chair.

Professor Treadwell, from the committee on the subject of meteorological observations, reported that Mr. Hall's observations are in due process of preparation for the press.

Professor W. B. Rogers made the following communication :

Proofs of the Protozoic Age of some of the Altered Rocks of Eastern Massachusetts, from Fossils recently discovered. "It is well known that the altered slates and gritty rocks which show themselves interruptedly throughout a good part of Eastern Massachusetts, have, with the exception of the coal-measures on the confines of this State and Rhode Island, failed hitherto to furnish geologists any fossil evidences of a paleozoic age, although from aspect and position they have been conjecturally classed with the system of rocks belonging to this period. Indeed, the metamorphic condition of these beds generally, traceable no doubt to the sienitic and other igneous masses by which they are traversed or enclosed, would naturally forbid the expectation of finding in them any distinguishable fossil forms.

"Lately, through the kindness of Peter Wainwright, Esq., residing in the neighborhood, I have been led to examine a quarry in the belt of siliceous and argillaceous slate which lies on the boundary of Quincy and Braintree, about ten miles south of Boston, and, to my great surprise and delight, I found it to be a locality of trilobites.

"It appears that for several years past the owner of the quarry, Mr. E. Hayward, and his family, have been aware of the existence of these so-called images in the rock, which from time to time they have quarried as a ballasting-material for wharves; but until now the locality has remained entirely unknown to science.

"The fossils are in the form of casts, some of them of great size, and lying at various levels in the strata. So far as I have yet explored the quarry, they belong chiefly, if not altogether, to one species, which, on the authority of Professor Agassiz, as well as my own comparison with Barrande's descriptions and figures, is a species of Paradoxides. Of its specific affinities I will not now speak, further