CACTACEJE 
49 
most of them lateral or inferior. Young spines reddish-grey with paler margins, older ones 
ashy. Fruit inch long ; seed rather regular, 2-24 lines in the transverse diameter, less than 
2 lines high, not beaked, commissure broader and more distinct than in any other of this sec¬ 
tion examined by us. Cotyledons in all the seeds examined oblique. 
This discription refers to the plant brought by the expedition from the Mojave river. Several 
years before Dr. Parry had described a plant discovered by him “on the hills and plains about 
San Felipe on the eastern slope of the California mountains,” which had been named after the 
discoverer. We presume that both plants were identical, but have to remark that Dr. Parry’s 
plant is much larger, having joints of 4-8 inches in length, with tubercles 6-12 lines long, 
spines whitish, half an inch long ; he describes the flowers as 1^ inch in diameter, greenish- 
yellow with green stigmata. Fruit not mentioned. Further investigation will be necessary to 
clear up those doubts. 
From 0. davata (which grows 8 or 9 degrees east and on much greater elevation) the Mojave 
species is distinguished by the shape of the joints, the color, much narrower, more numerous 
spines and the smaller more regular seeds, with the broad commissure. 
§ 2. Cylindrical. 
19. Opuntia Davisii, (sp. nov.) : caule dense lignoso ramosissimo divaricato adscendente, 
articulis junioribus erectis elongatis, basi attenuatis ; tuberculis oblongo-linearibus prominulis, 
setis stramineis tenerrimis ; aculeis interioribus 4-7 subtriangularibus rufis apice pallidioribus* 
vagina straminea laxa fulgida indusiatis divergentibus s. deflexis, aculeis gracilioribus inferiori- 
bus 5-6 ; bacca ovata pulvillis sub-25 setas stramineas aculeolosque paucos gerentibus ; umbilico 
lato. (Plate XYI, fig 1-4.) 
Common on the upper Canadian, eastward and westward of Tucumcari hills, near the Llano 
Estacado. A very much branched shrubby, somewhat procumbent, plant, with erect joints, 
about 18 inches high ; wood dense and hard ; joints 4-6 inches in length, and half an inch or 
more in thickness ; tubercles not very prominent, 7-8 lines long ; very slender bristles, forming 
a thick brush at upper end of pulvillus ; interior spines l-lj inches long, covered with a very 
loose glistening membranaceous sheath, which makes the plant an object of remark for a long 
distance ; lower spines 3-6 lines long. All the fruits seen on the route were sterile, and most 
of them elongated, 1-1£ inch long ; on many pul villi 1-4 sheathed spines were observed, which 
possibly are peculiar only to the sterile and proliferous fruits. 
We have named this well-marked and pretty species after our enlightened Secretary of War, 
Colonel Jefferson Davis, under whose auspices the expeditions for the exploration of a proper 
route for the Pacific railroad were organized, and were enabled to accomplish so much, not only 
for this specific object, but also for the elucidation of the natural history of this hitherto almost 
unknown country. 
20. 0 . echinocarpa, (sp. nov.) : caule retic'ulato-lignoso, erectiusculo, ramis numerosis paten- 
tissimis subinde pene decumbentibus, articulis ovatis basi clavatis, tuberculis ovatis prominent- 
ibus confertis, setis paucis stramineis ; aculeis albidis stramineo s. albido-vaginatis, majoribus 
sub-4 cruciatis, ceteri, minoribus 8-16 undique radiantibus ; floris flavi (?) ovario pulvillis 30-40 
villosis subaculeolatisque confertis stipato, sepalis sub-13, exterioribus ovatis acutis ; interim- 
bus obovatis mucronatis, petalis sub-8 obovatis obtusis s. subemarginatis denticulatis, stigmati- 
bus 6; bacca globoso-depressa s. hemispherica, late profundeque umbilicata pulvillis sub-40 
aculeolos vaginatos elongatos 8-12 gerentibus dense stipata floris, rudimento subpersistente 
coronata; seminibus subregularibus s. angulatis, crassis, late commissuratis, cotyledonibus 
parallelis. 
In the Colorado valley, near the mouth of Williams’ river. Mr. Schott found a stouter form 
further south. The more northern plant forms a low shrub 6-18 inches high, spreading, and 
7 r 
