124 ILLINOIS ACADEMY OP SCIENCE 



lection and identified by Dr. Griffiths as a good type is cor- 

 rect, then the description needs amending. It is tlie only 

 type that can be taken as 0. arizonica,, although it is more 

 plentiful in New Mexico than any place in Arizona and 

 very common in central Texas. 



There is also 0. discata. Griffiths. Rep. Mo. Bot. Gard. 

 266, 1908. Type locality also near Tucson, has proved by 

 cultivation to be only a more glaucous and spreading form, 

 with more circular joints than the true 0. engelmannii 

 Salm-Dyck. Bost. Jour. Nat. Hist. 6 ; 1850, which may be 

 regarded as typical in the St. Ulalia mountains. 



A peculiar instance also is the two names of Opuntia 

 microcarpa. 



O. microcarpa. Eng. Emory mil. recon. Folio 7, 1884. 

 Reported by Emory to be abundant in the Del Norte and 

 Gila regions, which would be in southwestern New Mexico. 



O. microcarpa. Schum. Gesem, Cacteen, 1899. Cul 

 Du Sac. Haiti, It is difficult to understand Drs. Britton 

 and Rose's opinion that Schumann's name is a homonym 

 of Engelmann's (Smith Misc. coll. 50:522). Thorough in- 

 vestigation evidences that no opuntia answering to Dr. 

 Engelmann's description exists in the given locality. Nor 

 has any been collected and authentically reported since. 

 Neither is there any herbarium specimen known. Engel- 

 mann's description was from a drawing which may not 

 have been accurate. But even then berries three to four 

 inches long are not small for an opuntia. 



O. pharacantha is the smallest opuntia in this locality 

 and Engelmannii cyclodes the most common. Therefore if 

 Schumann's plant proves a good species it could retain the 

 name and Engelmann's name could be regarded as a nom- 

 iiudum. There also appears to be a misunderstanding in 

 Opuntia griffithsiana. Mack, and 0. Mackenseni. Rose. 

 The descriptions of the two plants differ very little and 

 the specimens received from Prof. Mackensen differ less. 



By eliminating the many indefinite characters on which 

 many species have been based we can recognize the follow- 

 ing as good types of the tall growing opuntia. Engel- 

 mannii, N. W. Mexico and Ariz. (var. discata), dark 

 green and glaucous, short almost black bristles and gray 

 deflexed spines. 



