304 PROCEEDINGS OF THE AMERICAN ACADEMY 



tion. Joints 4-6 inches long, curved, 1 - H inches in diameter; 

 tubercles 1 - 1^- inches long; longest spines I5--2I inches long, 

 1^-1 line wide ; the exterior spines gradually smaller, and less angu- 

 lar. Fruit 2 - 2i 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 triangulate, cseteris 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 11-2 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 lonff. 



33. O. Grahami, E. 1. c. : radicibus fusiformibus ; articulis clava- 

 tis ; tuberculis oblongis ; foliis ovatis cuspidatis ; setis demum pluri- 

 mis ; aculeis gracilibus rubellis, interioribus 4-7 teretiusculis angu- 

 latisve, exterioribus 4-6 brevibus ; bacca pulvillos sub-30 setosissi- 

 mos gerente ; seminibus erostratis. 



Sand^ 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 2i lines in diameter or 

 more. Cotyledons regularly incumbent. 



34. O. BULBisPiNA, E. 1. c. : radicibus fusiformibus ; articulis par- 

 vis ovatis sa^pe ex apice proliferis fragilibus ; tuberculis ovatis brevi- 

 bus ; pulvillis parce setosis ; aculeis teretiusculis scabrellis basi bul- 

 bosis, interioribus 4 cruciatis, inferiore longiore, exterioribus 8-12 

 radiantibus. 



