292 PROCEEDINGS OF THE AMERICAN ACADEMY 



covered with spines 1-2 inches long ; joints 8 - 10 by 6 - 8 inches 

 in length ; spines 4- - IJ- inches long. Ovary with nearly 50 pulvilli, 

 while the foregoing species have not more than 20. 



ft Procumbentes. 



7. O. PROCUMBENS, E. & B. 1. c. : prostrata ; articulis orbiculato- 

 obovatis grandibus pallide viridibus ; pulvillis remotis setas stramineas 

 rigidas valde insequales et aculeos 2-4 validos compresses angulatos 

 stramineos basi obscuriores gerentibus. 



San Francisco mountains to Cactus Pass, in Western New Mex- 

 ico. Joints 9-13 inches long, always edgewise; pulvilli 14--2 

 inches apart ; spines 1-2 inches long. Similar to 0. Engelmanni^ 

 but prostrate, with more distant pulvilli, and stouter spines. No 

 flower or fruit seen. 



8. O. ANGUSTATA, E. & B. 1. c. : prostrata vel adscendens ; articulis 

 elongato-obovatis versus basin angustatis ; pulvillis remotis setas ful- 

 vas graciles aculeosque paucos (2 - 3) validos compresses stramineos 

 seu albidos versus basin rufos deflexos gerentibus ; bacca obovata 

 tuberculata ; seminibus magnis. 



From Zuni, west of the Rio Grande, westward to the Cajon Pass, in 

 the California mountains. — Joints 6-10 inches long, only 3 or 4 

 wide. Spines similar to those of the last species ; bristles much more 

 delicate. Fruit 1 J- inches long ; the umbilicus flat, but immersed. — 

 Well distinguished by the shape of the joints. 



* * * Fulvispince. 



9. O. MACROCENTRA, E. in B. C. R. : adscendens ; articulis magnis 

 suborbiculatis tenuibus ; pulvillis subremotis setas graciles breves ful- 

 vas gerentibus, summis solum aculeos 1-2 prselongos subcompres- 

 sos fusco-atros proferentibus; floris flavi ovario ovato ; stigmatibus 

 8 ; seminibus majusculis. 



Sand-hills on the Rio Grande near El Paso : fl. May. — Two or 

 three feet high, with very striking round joints, 5-8 inches in diame- 

 ter, and blackish spines as much as 2 or 3 inches long. Nearly allied 

 to the next species. 



10. 0. phjEACANTha, E. in PI. Fendl. : diffusa, adscendens ; articu- 

 lis obovatis crassis glaucescentibus ; pulvillis subremotis setas graciles 

 stramineas seu fuscatas longiores gerentibus, plerisque aculeos 2-5 

 p us minus compressos fuscos proferentibus ; floris flavi ovario abbre- 

 viato ; stigmatibus 8 ; bacca cuneata pyriformi ; seminibus majusculis. 



