OF ARTS AND SCIENCES. 283 



with bunches of spines which, as in the last species, on the flower are 

 indicated only by few and short bristles. Seed with tubercles conflu- 

 ent, and leaving pits between them. Nearly allied to the two last, 

 but sufficiently well distinguished by the characters given. 



15. C. Engelmanni, Parry in Sill. Journ. 1852 : ovato-cylindricus, 

 11-13 costatus ; aculeis radialibus sub-13 albidis, superioribus cfeteris 

 multo brevioribus, centralibus 4 longioribus angulatis rectis, 3 superi- 

 oribus fulvis arrectis, inferiore longiore albido porrecto seu deflexo ; 

 floribus lateralibus ; seminibus tuberculato-scrobiculatis. 



Var. iS. CHRYSOCENTRUS, E. & B. in P. R. R. : aculeis radialibus 

 12- 14 albidis, centralibus 3 superioribus validis vitellinis erectis, infe- 

 riore albo compresso deflexo. 



Var. y. VARiEGATUs, E. & B. 1. c. : aculeis radialibus sub-13 albi- 

 dis, centralibus 3 superioribus recurvatis divaricatis nigris corneo-vari- 

 egatis, inferiore longiore albo decurvo. 



Lower Gila, Colorado, and westward to the California mountains : 

 fl. June and July. — Stems 5-10 inches high ; radial spines slender, 

 3-6 lines, central ones 1-2 inches long. Fruit near the top of the 

 plant. — Dr. Bigelow collected a little farther north, on Bill Williams's 

 Fork, the two forms which I have put under /3. and y. ; though they 

 differ from the species by having the fruit lower down on the plant ; 

 the arrangement of the spines, however, is entirely identical. Var. (3. 

 has very stout central spines, 2-3 inches long, of a deep golden- 

 yellow color, and the lower one shorter. In var. y. the central spines 

 are only 1-2 inches long, much curved, and the upper ones white 

 and black mottled. 



* * Coccinei ; florihus diu noctuque apertis. 



16. ? C. GONACANTHUS, E. & B. in P. R. R. : ovatus, subsimplex, 

 7-costatus ; areolis remotis ; aculeis robustis angulatis ssepe curvatis, 

 radialibus 8 flavidis ssepe basi obscuris, summo cseteris multo majore 

 centralem multangulatum validum ssepe flexuosum subsequante. 



Near Zuni, in Western New Mexico, under cedars. — Radial spines 

 8-15 lines long, upper one and central spine 1^-2^- inches long, 

 remarkably stout, angular and channelled. — I have not seen the 

 flower of this plant, but place it here from its resemblance to the next 

 species ; on the other hand, it seems to be allied to C. Mojavensis. 



17. C. TRiGLOCHiDiATUS, E. in Wisl. Rep. : ovato-cylindricus, 6-7 

 costatus, parce ramosus ; areolis remotis; aculeis 3-6 robustis an- 



