OP ARTS AND SCIENCES. 



305 



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 OjmnticB glomeratcc^ rather than 

 here. Fruit unknown. 



§ 2. CylindriccR : adscendentes vel erectse : articuli longiores, ovato- 

 cylindrici seu elongati : textura lignosa compacta, tubum reticula- 

 tum vel truncum compactum formans : flores magni seu parvi, pur- 

 purei vel raro flavi : bacca sicca vel subcarnosa, floris rudimenta 

 plerumque dejiciens, aculeata seu inermis. 



* PolyacanthcB : lignum plerumque reticulato-tubulosum ; articuli 

 crassiores distincte tuberculati : aculei plures seu plurimi : flores 

 plerumque rubri : semina immarginata. 



t Humiliores : diffuse ramosse : articuli subclavati : flores plerumque 

 flavidi : baccse siccse, aculeatse. 



35. O. Davisii, E. & B. in P. R. Rep. : caule dense lignoso ramo- 

 sissimo divaricato ; articulis junioribus erectis elongatis basi attenuatis ; 

 tuberculis oblongo-linearibus ; aculeis interioribus 4-7 subtriangu- 

 laribus 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. Joints 4-6 inches long, 

 rather slender ; tubercles 7-8 lines long ; interior spines 1-1^ inch- 

 es in length; lower ones 3-6 lines long. Fruits (all sterile, and per- 

 haps not properly developed) an inch or more in length. 



36. O. ECHiNocARPA, E. & B. 1. c. : erectiuscula ; ramis numero- 

 sis patentissimis ; articulis ovatis basi clavatis ; tuberculis ovatis con- 

 fertis ; aculeis majoribus sub-4 albidis stramineo-vaginatis, 8-16 mi- 

 noribus undique radiantlbus ; flore flavo (?) ; bacca globosa depressa 

 seu hemisphaerica late profundeque umbilicata pulvillis sub-40 aculea- 

 tissimis stipata ; semlnibus late commissuratis. 



Var. i3. MAJOR : elatior ; articulis elongatis ; aculeis longioribus 

 laxius vaginatis paucioribus ; baccis globosis pulvillos pauciores (25) 

 gerentibus. 



In the valley of the Lower Colorado ; /3. in Sonora. — Var. a. is a 



VOL. III. 39 



