938 CONTKIBUTIONS FKOM THE NATIONAL HEKBAEIUM. 



13. Echinofossulocactus obvallatus (DC.) Lawrence in Loud. Gard. Mag. 17: 

 317. 1841. 



Echinocactus ohvallaUis DC. Prodr. 3: 462. 1828. 



Hidalgo. 



Obovoid to globose, depressed at apex ; ribs about 2.5, rather thin and un- 

 dulate ; spines about 8, 4 spines subulate, ascending or spreading, 4 spines 

 short, perhaps not one-fourth the length of the longer ones ; flowers central, 

 very large ; perianth segments linear-oblong. 



14. Echinofossulocactus pentacanthus (Lem.) Britt. & Rose, Cactaceae 3t 

 115. 1922. 



Echhwcactus pentacantJms Lem. Cact. Aliq. Nov. 27. 1883. 



Echinocactus Mceras Jacobi, Allg. Gartenz. 16: 370. 1848. 



Reported from San Luis Potosi and Hidalgo. 



Simple, depressed-globose to short-cylindric. more or less glaucous ; ribs 

 about 25, perhaps even 40 to 50 ; areoles only a few to the rib ; spines 5, 

 unequal, grayish red, hardly angled, flattened ; 3 upper spines erect op 

 spreading; 2 lower spines much slenderer and shorter than the upper; flowers 

 large for this group, deep violet ; perianth segments with white margins. 



15. Echinofossulocactus crispatus (DC.) Lawrence in Loud. Gard. Mag. 17: 

 317. 1841. 



Echinocactiis crispatus DC. Prodr. 3: 461. 1828. 



Reported from Hidalgo. 



Plants obovoid, somewhat depressed at apex ; ribs about 25, more or less 

 folded, simiewhat undulate ; spines 10 or 11, rigid, unequal ; flowers central, 

 rather small; perianth segments in 2 series, purplish, oblong-linear, acute; 

 flower tube covered with imbricate scales. 



The following species have been referred here by some authors : Echino- 

 cactus flexispinus Salm-Dyck (Cact. Hort. Dyck. 1849. 159. 1850) ; E. undu- 

 latus Dietr. (Allg. Gartenz. 12: 187. 1844. 



16. Echinofossulocactus dichroacanthus (Mart.) Britt. & Rose, Cactaceae 3: 

 117. 1922. 



Echinocactus dichroacanthus Mart. ; Pfeiff. Enum. Cact. 62. 1837. 



Hidalgo. 



Plant obovoid, dull green, 15 cm. high, 10 cm. in diameter, somewhat um- 

 bilicate at apex; ribs 32, thin, acute, undulate, somewhat wavy; areoles only 

 a few on each rib, white-tomentose ; upper spines 3, erect, flattened, purplish ; 

 radial spines 4 to 6, white. 



17. Echinofossulocactus anfractuosus (Mart.) Lawrence in Loud. Gard. Mag. 

 17: 317. 184L 



Echinocactus anfractuosus Mart. ; Pfeiff. Enum. Cact. 63. 1837. 



Hidalgo. 



Plant simple, somewhat longer than broad, 12.5 cm. long, 6 cm. in diameter, 

 dull green; ribs many (about 30, according to Schumann), compressed, wavy, 

 each bearing only a few areoles ; spines somewhat curved, straw-colored with 

 brown tips ; radial spines 7, stout, the 3 upper radials much larger, about 

 3 cm. long, the 4 lower radials slender ; central spine solitary, 2.5 cm. long, 

 brownish ; perianth segments purple with white margins. 



18. Echinofossulocactus tricuspidatus (Scheidw.) Britt. & Rose, Cactaceae 

 3: 117. 1922. 



Echinocactus tricuspidatus Scheidw. Allg. Gartenz. 9: 51. 1841. 

 Echinocactus melmsianus Wegener, Allg. Gartenz. 12: 65. 1844. 

 San Luis Potosi. 



