SAXIFRAGA UNALASCHENSIS, Sternb. Saxifr. Suppl. ii. 9, which Engler appends to S. Dahurica, is an Aleutian and Arctic Alaskan species, recently collected by Dall and by Muir, also by Dr. Steineger at Copper Island on the Asiatic side. It must also be S. flabellifolia, R. Brown in Torr. & Gray, Fl. i. 569.

SAXIFRAGA LYALLI, Engler, Monogr. Saxifr. 141, a well-marked species, of the northern Rocky Mountains, found also by C. Wright on the Asiatic side of Behring Strait.

SAXIFRAGA NUDICAULIS, Don, Monogr. Saxifr. 366. This is S. neglecta, Bray in Sternb. Saxifr. Suppl. i. 9, ii. 36, as well as S. vaginalis, Turcz. in Ledeb. Fl. Ross. ii. 220. Don's plant was collected by Nelson, probably in Arctic Alaska (as the name is now used), and Menzies collected it in the same region. Our specimens (coll. Dall and C. Wright) are from the Asiatic shore and islands, and from Ajan, by Tiling. Don's name and that in Sternberg were published in the same year (1822); but, as Don's memoir was "Read, Feb. 20, 1821," we may perhaps assume some priority in publication. SAXIFRAGA PUNCTATA, L. (with synonymy as detailed by Engler), is an unmistakable species. But it passes by many gradations into

Var. NANA, an Arctic form, also high alpine in the more northern Rocky Mountains, with scape barely a span high, bearing a simple and small cyme or a close glomerule of few flowers, the leaves much reduced in size and only 7-11-lobulate. This abounds on the coast of Arctic Alaska, within Behring Strait, and answers to S. Nelsoniana, Don, only more dwarfed, and the inflorescence condensed; so that no one would refer it to S. punctata, except for the intermediate forms. Burke collected a similar form on the higher Rocky Mountains.

Var. ACUTIDENTATA, Engler, is founded on a plant of Lyall's collection from "Cascade Mountains, South Clear Creek." A specimen in our herbarium which agrees with the character is ticketed "Rocky Mountains, lat. 49°, at 6,500 feet alt." It is a large form, with the slightly cordate base of the leaves abruptly decurrent into a partly winged petiole, the numerous teeth unusually coarse and acute: and some smaller leaves from the rootstock are cuneate.

SAXIFRAGA FRAGARIOIDES, Greene in Bull. Torr. Club. viii. 121 (1881), a most peculiar species, is one of Mr. Pringle's discoveries, in the northern part of California, on a high mountain west of Mt. Shasta. "The leaves," as Mr. Greene states, "are a most precise imitation of the leaflets of the common Wild Strawberry, both as regards their form, color, texture, and even size." The scape is foliosebracteate, and the lignescent tufted rootstocks are peculiar.

III.

A CONTRIBUTION TO OUR KNOWLEDGE OF PALEOZOIC ARACHNIDA.

BY SAMUEL H. SCUDDER.

Communicated June 11th, 1884.

UNTIL a very recent period discoveries of fossil Arachnida in the older rocks had been exceedingly few, and the first and only attempt to show their relations to each other and to living forms was made in a recent paper by Karsch,* occasioned by his description of a new generic type. Yet the first discovery of carboniferous forms dates back to Corda, who described † a scorpion found by Sternberg at Chomle in Bohemia, a discovery which justly awakened at the time the widest interest.

Karsch, in his brief attempt to bring into connected order the discoveries of the past, has established for the bulk of the species which do not belong to the scorpions the order Anthracomarti, divided into two families, the Architarboida and Eophrynoida.

The following is a succinct account of his arrangement:

ORDER 1. ARANEÆ.

Body composed of two principal masses, of which the front (cephalothorax) is unsegmented, and the hinder (abdomen), unsegmented beneath, has at the most a single segmented dorsal plate.

Fam. LIPHISTIOIDÆ Thor.

Abdomen with segmented dorsum.

Protolycosa anthracophila Roemer (Silesia).

ORDER 2. OPILIONES.

Body forming either a single mass or two segment-complexes, always separated into segments both above and below.

Zeitschr. deutsch. geol. Gesellsch., 1882, p. 556.

↑ Verhandl. Gesellsch. vaterl. Mus. Böhmen, 1835, p. 35.

Fam. TROGULOIDÆ.

Dorsal segments of the abdomen each with three transverse fields. Palpi and mandibles not visible from above.

Kreischeria Wiedei Geinitz (Saxony).

ORDER 3. ANTHRACOMARTI Karsch.

Body composed of two main divisions, of which the front one is unsegmented, the hinder segmented. Palpi visible from above.

Fam. ARCHITARBOIDÆ Karsch.

Number of abdominal segments equal above and below. Integument smooth.

ARCHITARBUS Scudder.

Cephalothorax and abdomen not separated by a lateral constriction. A. rotundatus Scudder (Illinois), A. subovalis Woodward (England), A. silesiacus Roemer (Silesia).

ANTHRACOMARTUS Karsch.

Cephalothorax and abdomen distinctly separated by a lateral con

striction.

A. Völkelianus Karsch (Silesia).

Fam. EOPHRYNOIDÆ Karsch.

Number of dorsal and ventral segments of the abdomen unequal, more numerous above. Integument tuberculate.

Eophrynus Prestvicii (Buckl.) Woodward (England).

ORDER 4. SCORPIONES.

Body separated into three main divisions, the cephalothorax unsegmented, the abdomen segmented and furnished with a segmented tailappendage (pcstabdomen).

Eoscorpius anglicus Woodward (England), E. carbonarius Meek and Worthen (Illinois), Microlabis Sternbergi Corda (Bohemia), Cyclophthalmus senior Corda (Bohemia), Mazonia Woodiana Meek and Worthen (Illinois).

While justified in the main in this arrangement, Karsch's definitions of the groups are both insufficient, and to some extent based on altogether subordinate characteristics. The discovery of new American

forms enables me to supplement, and, as I believe, to improve these, and accordingly the following systematic sketch of paleozoic Arachnida has been prepared, into which have been thrown such suggestions and new facts as have come to hand.

ORDER ANTHRACOMARTI Karsch.

Body more or less depressed, the cephalothorax and abdomen distinctly separable. Cephalothorax frequently made up in large part of pedigerous segments more or less wedge-shaped, and visible above as well as below, the arrangement of which corresponds to that of the сохӕ. The abdomen forms a single mass, and is composed of a variable number of visible segments, ranging from four to nine. Palpi not much longer than the legs, simply terminated.

Fam. ARTHROLYCOSIDÆ Harger.

Cephalothorax orbicular, twice as large as the abdomen. Coxæ radiating from a central pit. Abdomen oval, much narrower at base than the cephalothorax, with no longitudinal sculpturing, and composed of seven segments. No abdominal appendages.

ARTHROLYCOSA Harger.

Arthrolycosa antiqua Harger, Amer. Journ. Sc. Arts, (3,) vii. 219223 (fig.), 1874. Mazon Creek, Illinois.

In his description of this arachnid, Harger inclines to the belief that the terminal segment of the palpus is chelate. He says (loc. cit.): "The third [joint] is broken near its proximal articulation, and the connection of this appendage with what seems to be its distal cheliform segment is unfortunately imperfect. This segment is also poorly preserved, and the articulation of its digit is only to be seen with a good magnifier and in a certain light. . . . I do not, however, consider the forcipulate character of this segment beyond a doubt. It is perhaps not improbable that it may have been modified much as in the males of ordinary spiders, and not truly forcipulate."

Having reason, by its undoubted relationship to other forms of Anthracomarti, to doubt the forcipulate character of the palpus, of which Harger speaks so doubtfully, Professor Marsh kindly permitted me to study the type in Yale College Museum, and I find on close examination that not only is the joint in question not chelate, but it terminates by a straight, transverse suture, and is followed by a portion of another, apparently short, terminal joint.

Fam. POLIOCHERIDÆ nov. fam.

Cephalothorax quadrate, not much smaller than the abdomen. Coxæ radiating (apparently) from a median line. Abdomen rounded, of equal breadth with the cephalothorax, with very indistinct or no longitudinal sculpturing, and composed of only four segments, of which the basal is very short. No abdominal appendages.

POLIOCHERA nov. gen.

Cephalothorax scarcely longer than broad, slightly narrowing anteriorly, the front square. Legs stout, moderately long. Abdomen full, at base as broad as the cephalothorax, broadening slightly behind, fully rounded, the first segment about one third the length of the others, which are equal.

Poliochera punctulata nov. sp. Body minutely, deeply and uniformly punctate throughout, excepting on the narrow first abdominal segment, which is smooth. Legs similarly punctate. Length 15 mm., greatest breadth 7.5 mm. Mazon Creek, Illinois (R. D. Lacoe, No. 1845). A fuller description and figure will be given at another time.

Fam. ARCHITARBOIDE Karsch.

Cephalothorax of variable form, but at least half as large as the abdomen. Coxæ radiating from a middle point or line, or from a triangular sternal piece, its base on the abdominal margin. Abdomen. orbicular or oval, at base as broad or nearly as broad as the cephalothorax, with a lateral ridge on each side converging toward the anus, the surface moderately smooth; segments seven to nine in number, the basal ones visible below, though often extremely shortened in the middle; no abdominal appendages.

GERAPHRYNUS nov. gen.

Cephalothorax fusiform, angulated in front, nearly as large as the abdomen. Coxæ radiating from a median line. Palpi slenderer than the legs, longer than the cephalothorax, springing from its extreme front and of uniform size throughout. Abdomen subfusiform, composed of nine segments, rounded behind, with no constriction at the base; a large triangular post-thoracic plate, crowding the middle of the first five short segments out of a straight transverse line. Readily distinguished from Architarbus by its produced and angulate cephalothorax.

Geraphrynus carbonarius nov. sp. Cephalothorax faintly punctu