OF ARTS AND SCIENCES. 307 



lines long; spines''l-l|- inches long, hiding the whole plant with 

 their lustrous sheaths. Flower about one inch or less in diameter. 

 Fruit fleshy, 1-1^ inches long, usually sterile. Seeds smaller than 

 in any other Opuntia examined, 1 - 1^ lines long. 



40. O. BiGELOVii, E. in P. R. R. : ramis erectis adscendentibusve ; 

 articulis ovato-cylindricis pallide virescentibus congestis ; tuberculis 

 subhemisphosricis depressis confertis ; aculeis 6-10 robustioribus et 

 totidem gracilioribus inferioribus ; ovario tuberculato ; bacca tuber- 

 culata subinde (sterili ?) aculeolata ; seminibus parvis. 



On Williams's River, of the Californian Colorado. — Stem 3-4 

 inches thick and 10 - 12 feet high ; the branches forming a dense 

 contracted head, with joints 2-6 inches long ; tubercles 3-4 lines 

 long ; larger spines about an inch long, smaller ones 4-7 lines long. 



The three foregoing species represent this subsection west of the 

 California mountains, and east of them both south of the Gila and 

 north of it, and seem to be well distinguished from one another by the 

 characters indicated. 



f ft Cristatm : frutescentes vol arborescentes : articuli cylindrici : tu- 

 bercula plerumque cristata prominula : flores purpurei : baccse in- 

 ermes seu rarius aculeatse. 



41. O. Whipplei, E. & B. in P. R. R, : caule erecto seu rarius 

 subprocumbente divaricato-ramoso ; articulis cylindricis ; tuberculis 

 ovatis confertis ; aculeis brevibus cinereo- seu stramineo-vaginatis, 1 - 

 4 majoribus, 2-8 brevioribus deflexis vel radiantibus ; flore rubro ; 

 bacca subglobosa tuberculata flava inermi ; seminibus regularibus. 



Var. a. LiEviOR : humilior, aculeis paucis deflexis. 



Var. /3. spinosior: elatior, aculeis plurimis radiantibus. 



From Zuni westward to Williams's River (a.), and south of the Gila 

 (jS.) : fl. in June. — The first state is from a few inches to 3 - 6 feet 

 high ; the second forms small trees 8-10 feet high. Joints 5- - f inch 

 in diameter ; tubercles about 5 lines long ; spines very variable, be- 

 tween 3 and 9 lines long. Flower (of var. /3.) 1;^- \^ inches in di- 

 ameter. Fruit about an inch long. 



42. O. ARBORESCENs, E. in Wish Rep. (O. stellata, Salm.) : arbo- 

 rescens ; ramis verticillatis horizontalibus vel pendulis ; articulis verti- 

 cillatis cylindricis ; tuberculis cristatis prominentibus ; aculeis 8-30 

 stellato-divaricatis ; flore purpureo magno ; bacca subhcmisphserica 

 tuberculato-cristata flava inermi ; seminibus regularibus. 



