516 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vol. 50 



OPUNTIA MICRODASYS Lehm. 



I 

 Opuntia microdasys Lehm. Ind. Sem. Hamburg. 1827. 

 Opuntia pulvinata DC. Mem. Mus. Paris 17: 119. 1828. 



Type locality: Mexico. 

 Distribution : Coahuila. 



OPUNTIA RUFIDA Engelm. 



Opuntia rufida Engelm. Proc. Am. Acad. 3:298. 1856. 

 Opuntia microdasys rufida Schum. Gesamtb. Kakteen 706. 1899. 



Type locality : About Presidio del Norte, on the Rio Grande. 

 Distribution : Texas, Chihuahua. 



OPUNTIA MACDOUGALIANA Rose, sp. nov. 



Plant about 4 meters high, with a distinct cylindric trunk branch- 

 ing from near the base; joints oblong, 30 cm. long by 8 to 10 cm. 

 broad, softly pubescent; areoles distinct, small; spines generally 4, 

 one much longer (2.5 to 4 cm. long), somewhat flattened, yellowish, 

 becoming whitish in age ; glochides short, numerous, yellow ; fruit 

 globular to oblong, 5 cm. long, the surface divided into diamond- 

 shaped plates, red, with a broad deep cup at apex, the numerous 

 small rounded areoles filled with clumps of yellow glochides, very 

 rarely with one or two spines. 



Type in U. S. National Herbarium, no. 453,485, collected by Rose 

 and Painter near Tehuacan, Mexico, August and September, 1905 

 (no. 9990). 



Named for Dr. D. T. MacDougal, of the Carnegie Institution of 

 Washington, who has photographed many of the cacti of Mexico, 

 including this one, and to whom we are indebted for important 

 cooperation in this investigation. 



OPUNTIA NELSONII Rose, sp. nov. 



Stems 1 to 4 meters high; joints flattened, oblong to pear-shaped 

 in outline, 15 to 20 cm. long by 10 to 15 cm. broad near the top, 

 pubescent, pale yellowish green in herbarium specimens; areoles 2 

 to 3 cm. apart; spines 2 to 6, yellow, becoming white in age, very 

 unequal, the longer ones 3 to 4 cm. long ; bristles many, yellow, be- 

 coming brownish; flowers rather small; petals yellow, 10 to 15 mm. 

 long; ovary pubescent, bearing many yellowish brown bristles; 

 fruit "dark red." 



Said to be the common species in the region between Juajuapam, 

 Oaxaca, and Retlatzingo, Puebla, altitude 1,440 to 1,950 meters, 

 where it was collected by E. W. Nelson November 19, 1894 (no. 



