or without smaller ones, which never occurs in any form of O. Missouriensis, where a large number of small setaceous spines is found, whether larger ones are present or not. Fruit 9 lines in diameter, with a small flat umbilicus. Seeds 2 lines in diameter.

** Articuli tumidi ovati.

25. O. ErinaceA, E. & B. 1. c.: adscendens; articulis ovatis seu teretiusculis; pulvillis confertissimis omnibus armatis; aculeis 5-10 gracilibus rubellis, 3-5 elongatis; bacca ovata aculeolata; seminibus magnis subregularibus.

Near the Mojave, between the Colorado and the Californian mountains. Joints 2-2 inches long, 1-1 broad, and thick, sometimes almost cylindrical, densely covered with large white pulvilli, which are only 2-3 lines apart. Spines 6-14 or even 20 lines long, slender but stiff. Fruit an inch or more in length. Seeds nearly 3 lines in diameter.

26. O. ARENARIA, E. in B. C. R.: adscendens; articulis obovatis compressis seu teretiusculis tuberculatis; foliis minutis; pulvillis subconfertis pallide setosis; aculeis 1-4 robustioribus albidis fuscatisve, cum inferioribus brevioribus 2-6 albis; floris sulphurei ovario obovato; petalis emarginatis; stigmatibus 5; bacca oblonga spinulosa; umbilico infundibuliformi; seminibus magnis irregularibus.

-

Sandy bottoms of the Rio Grande near El Paso: fl. May. Spreading 2-3 feet, 1 foot high; roots stout, creeping horizontally; joints 1-3 inches long, 1-2 inches wide, and thick, more strongly tuberculated than the allied species; leaves only a line long; pulvilli 3-5 lines apart, very bristly, especially on the old joints; upper spines 9-15 lines long. Flower 2-2 inches in diameter. Fruit about an inch long. Seeds 21 - 3 lines in diameter. This is the only one of our Cactaceae on which the Cochenille has been found.

27. O. FRAGILIS, Haw. (Cactus fragilis, Nutt.): subdecumbens ; articulis parvis ovatis subcompressis tumidis vel subglobosis vix tuberculatis nitide viridibus; foliis minutis; pulvillis subconfertis magnis albo-tomentosis, vix setulosis; aculeorum 1-4 robustiorum summo valido angulato fuscato porrecto, ceteris debilioribus pallidioribus patulis seu radiantibus; aculeis inferioribus 2-6 gracilibus albis radiantibus; floribus minoribus; bacca ovata vix spinulosa, umbilico infundibuliformi; seminibus paucis magnis subregularibus.

Fertile prairies, or sterile places, on the Upper Missouri and Yellowstone, to the mountains and south to Santa Fé. - Size and shape of the joints variable; fruit-bearing joints compressed, 1-2 inches long, 1-14 wide, and thick; others smaller and more tumid. Leaves a line long, hardly longer than the large pulvilli, red. Pulvilli 4-6 lines apart, bristles very few, short, whitish, on the old joints a little more numerous, coarser, dirty yellow. Lower radiating spines 2-4 lines long; central spines 6-10 lines long, the other interior spines 3-8 lines long, often similar to the smaller lower spines. Fruit rather fleshy through the winter, getting dry in spring, nearly an inch long, with 20-25 pulvilli, of which only the upper ones bear a few short spines. Seeds few, usually only 5 or 6 in each fruit, 3 lines in diameter, with a wide and thick obtuse corky margin. — Often sterile, but abundantly propagated by the fragile joints.

28. O. BRACHYARTHRA, E. & B. 1. c. : adscendens; articulis ovatis orbiculatisve tumidis sæpe subglobosis tuberculatis; pulvillis confertis parce setulosis; aculeis 3-5 validioribus 1–2 fuscatis patulis vel suberectis, cæteris deflexis; floris parvi ovario subgloboso pulvillos 12 - 15 vix aculeolatos gerente; stigmatibus 5.

Inscription Rock near Zuni. - The short and tumid joints (10-15 lines long) resemble the joints of a finger; the pulvilli 2-4 lines apart, even in the oldest parts of the plant with very few bristles; longer spines 9-12 lines long, terete. Ovary less than half an inch. long. Flower apparently an inch in diameter. Perhaps too near O. fragilis; but in the absence of good flowers and fruit, it is impossible to say whether it does not belong to even a different section, perhaps to the Glomerata, Salm.

Subgen. 3. CYLINDROPUNTIA, E. in B. C. R. Articuli cylindracei : flores magni vel parvi: bacca plerumque sicca: semina immarginata seu vix marginata: embryo circa albumen copiosius subcircularis ; cotyledones contrariæ seu obliquæ, subinde parallelæ.

1. Clavate: prostrata: articuli breves, clavati, adscendentes, textura lignosa laxe reticulata: flores flavi majusculi: bacca sicca, pulvillis numerosis setosissimis stipata, floris rudimentis persistentibus coronata.

29. O. CLAVATA, E. in Wisl. Rep.: articulis breviter clavatis læte viridibus; tuberculis ovatis; foliis subulatis minutis; aculeis albidis.

scabrellis, interioribus 4-7 complanatis, inferioribus deflexis latioribus. supra striatis subtus carinatis, superiore triangulato erecto; aculeis exterioribus 8-10 gracilioribus undique radiantibus; baccæ pulvillis setosissimis; seminibus rostratis.

Santa Fé and Albuquerque, on the plateaux: fl. in June and July. -Dense spreading masses, with joints 1-2 inches long; tubercles 6-8 lines long; larger spines 6-15 lines long, and the broadest one - 1 lines wide. Flower 2 inches in diameter. Fruit yellow, 1– 1 inches long, an inch in diameter, covered with 30-50 large pulvilli. Seed 2-3 lines in the longest diameter. Cotyledons mostly oblique, or, as in most other Opuntia, incumbent. (The expression is not etymologically correct, but I use it to designate the direction of the face of the cotyledons towards the radicle.)

30. O. PARRYI, E. in Sillim. Journ. 1852: prostrata; articulis ovatis basi clavatis; tuberculis oblongo-elongatis; setis paucis; aculeis angulatis scabris rubellis demum cinereis, interioribus sub-4 validioribus compressis, exterioribus 4-8 divergentibus, extimis 6-10 gracilibus radiantibus; bacca ovata pulvillis sub-40 setosissimis stipata; seminibus erostratis.

On the Mojave, west of the great Colorado. Joints 21-3 or 4 inches long, attenuated below and somewhat so above; tubercles 9 lines long; inner spines 12-16 lines long, and the larger ones somewhat flattened, but less than a line wide; exterior spines 3-8 lines long, in two series. Fruit 1 inches long. Seeds about 2 lines in diameter. The original specimens of Dr. Parry were found farther south, near San Felipe. He describes the joints as 4 - 8 inches long, with shorter whitish spines or tubercles 6-12 lines long, and the flower as greenish-yellow. The Mojave plant is nearly allied to the last species, but may be distinguished by the shape of the joints, the narrower, darker-colored, more numerous spines, and the smaller and more regular seeds.

31. O. EMORYI, E. in B. C. R.: articulis cylindricis basi clavatis glaucis; tuberculis oblongo-linearibus elongatis; setis paucis; aculeis plurimis rufis, interioribus 5-9 validioribus triangulatis, compressis, exterioribus 10-20 pluriseriatis undique radiantibus; floribus flavis extus rubellis; bacca pulvillos 35-50 setosissimos inferiores aculeolatos gerentibus; seminibus valde inæqualibus irregularibus.

Arid soil, from El Paso through Sonora to the desert of the Colorado fl. August and September. The stoutest species of this sec

tion. Joints 4-6 inches long, curved, 1-14 inches in diameter; tubercles 1-1 inches long; longest spines 1-2 inches long,

-1 line wide; the exterior spines gradually smaller, and less angular. Fruit 2-2 inches long, partly armed with spines 4-8 lines long. Seeds from 2 to 3 lines in diameter. Cotyledons oblique or accumbent.

32. O. SCHOTTII, E. 1. c.: articulis clavatis; tuberculis elongatis ; pulvillis pauci-setosis; aculeis rubellis scaberrimis, interioribus sub-4 cruciatis, superiore triangulato, cæteris supra planis subtus convexis, latioribus; exterioribus 8-10 radiantibus gracilibus; bacca ovata pulvillos 35-40 pauci-setosos gerente; seminibus rostratis.

On the arid hills near the mouth of the San Pedro and Pecos, Western Texas. - Distinguished by the broad and very rough spines, which are dirty red, the larger ones with a white margin, and by the smaller number of bristles both on the pulvilli of the joints and of the fruit, where they are mostly turned upwards. Joints 2 inches long; tubercles 8-9 lines long; spines 1-2 inches long; the radiating ones only 4-9 lines long. Seeds 2 lines in diameter. Cotyledons oblique.

Dr. Gregg has collected a similar plant near San Luis Potosi ; which at present I know not how to distinguish from O. Schottii. The spines are stout, perhaps less rough, and narrower, 12-15 in number; some of them borne on the upper margin of the pulvillus, which I have never seen in O. Schottii. Tubercles an inch long.

33. O. GRAHAMI, E. 1. c.: radicibus fusiformibus; articulis clavatis; tuberculis oblongis ; foliis ovatis cuspidatis; setis demum plurimis; aculeis gracilibus rubellis, interioribus 4-7 teretiusculis angu latisve, exterioribus 4-6 brevibus; bacca pulvillos sub-30 setosissi mos gerente; seminibus erostratis.

Sandy bottoms of the Rio Grande near El Paso: fl. June. — Joints 1-2 inches long; tubercles 6-7 lines long; leaves thicker and in proportion shorter than in most other species, nearly 2 lines long. Fruit similar to that of O. clavata. Seed 2 lines in diameter or more. Cotyledons regularly incumbent.

34. O. BULBISPINA, E. 1. c.: radicibus fusiformibus; articulis parvis ovatis sæpe ex apice proliferis fragilibus; tuberculis ovatis brevi bus; pulvillis parce setosis; aculeis teretiusculis scabrellis basi bulbosis, interioribus 4 cruciatis, inferiore longiore, exterioribus 8-12 radiantibus.

Saltillo, Mexico.- Spreading masses with joints an inch long or less; tubercles 4-6 lines long; interior spines 4-6, exterior ones 1-3 lines long. Apparently near the South American O. pusilla, Salm., and perhaps belonging to the Opuntia glomeratæ, rather than here. Fruit unknown.

2. Cylindrica: adscendentes vel erecta: articuli longiores, ovatocylindrici seu elongati: textura lignosa compacta, tubum reticulatum vel truncum compactum formans: flores magni seu parvi, purpurei vel raro flavi: bacca sicca vel subcarnosa, floris rudimenta plerumque dejiciens, aculeata seu inermis.

* Polyacanthæ : lignum plerumque reticulato-tubulosum; articuli crassiores distincte tuberculati: aculei plures seu plurimi: flores plerumque rubri: semina immarginata.

† Humiliores: diffuse ramosæ : articuli subclavati: flores plerumque flavidi: baccæ siccæ, aculeatæ.

35. O. DAVISII, E. & B. in P. R. Rep. caule dense lignoso ramosissimo divaricato; articulis junioribus erectis elongatis basi attenuatis; tuberculis oblongo-linearibus; aculeis interioribus 4-7 subtriangularibus rufis vagina straminea laxa indusiatis divergentibus; aculeis inferioribus 5-6 gracilibus; bacca ovata pulvillis sub-25 aculeigeris stipata.

On the Llano Estacado, near the Upper Canadian River; common. - Spreading and somewhat procumbent, about 18 inches high; the only one in this section with dense wood. rather slender; tubercles 7-8 lines long; es in length; lower ones 3-6 lines long. haps not properly developed) an inch or more in length.

Joints 4-6 inches long, interior spines 1-1 inchFruits (all sterile, and per

36. O. ECHINOCARPA, E. & B. 1. c.: erectiuscula; ramis numerosis patentissimis; articulis ovatis basi clavatis; tuberculis ovatis confertis; aculeis majoribus sub-4 albidis stramineo-vaginatis, 8-16 minoribus undique radiantibus; flore flavo (?); bacca globosa depressa seu hemisphærica late profundeque umbilicata pulvillis sub-40 aculeatissimis stipata; seminibus late commissuratis.

Var. B. MAJOR elatior; articulis elongatis; aculeis longioribus laxius vaginatis paucioribus; baccis globosis pulvillos pauciores (25) gerentibus.

In the valley of the Lower Colorado; B. in Sonora.

- Var. a. is a