THE CACTAC3AE. 



5. Nyctocereus oaxacensis sp. nov. 



Stems branching, slender, 2 to 3 cm. in diameter; ribs 7 to 10, rather low; areoles 10 mm apart; 

 radial spines 8 to 12, 4 to 15 mm. long, slender, brownish; centrals 3 to 5; flowers 8 to 10 cm. long, 

 "whitish inside, dirty purplish or reddish outside"; perianth-segments linear to oblong, rounded at 

 apex; stamens not extending nearly as far as the perianth-segments; ovary densely covered with 

 brownish bristly spines. 



Collected by E- W. Nelson about Lagunas, Oaxaca, Mexico, altitude 255 meters, 

 June 5, 1895 (No. 2543, type). 



We refer here tentatively another specimen also collected by Mr. Nelson near Huilo- 

 tepec, Oaxaca, altitude 30 meters, May 4 to 11, 1895 (No. 2585). 



Washington. 



21. BRACHYCEREUS gen. nov. 



Stems low, forming candelabrum-like masses; branches numerous, cylindric; ribs many, low, 

 with closely set areoles bearing felt and numerous acicular spines ; flowers narrow-funnelform, bear- 

 ing small scales which subtend large spiny areoles ; outer perianth-segments lanceolate ; inner perianth- 

 segments very narrow, long-acuminate, described as possibly white but more likely yellow; filaments 

 very short; ovary obliquely subglobose, bearing scattered spiny areoles; fruit ellipsoid, very spiny, 

 but in age probably naked. 



The name is from the Greek, meaning short-cereus. 



Only one species is known, native of the Galapagos Islands. 



1. Brachycereus thouarsii (Weber). 



Cereus thouarsii Weber, Bull. Mus. Hist. Nat. Paris 5: 312. 1899. 



Cereus nesioticus Schumann in Robinson, Proc. Amer. Acad. 38: 179. 1902. 



