CACTACE^ OF MEXICO SAFFORD. 535 



thing Avas parched and dry at this season, and tlie area had been 

 burned over, the guide said, to destroy the " infernal " Opuntia tuni- 

 cata, the same species I had collected at Aguascalientes (pi. 10, 

 fig. 5). Here it is called abrojos, a name applied to various spiny 

 plants in Spain and Mexico, signifying " caltrops." 



On visiting the Instituto Medico of the City of Mexico I had the 

 pleasure of meeting Prof. Gabriel V. Alcocer, who kindly presented 

 me with a copy of the valuable Sinonomia Vulgar y Cientifica de las 

 Plantas Mexicanas, a work to which he contributed as collaborator of 

 the late Dr. Jose Ramirez. It was a great disappointment to me to 

 find that little effort had been made to form a collection of living 

 Cactacese at the Instituto Medico. At the Museo Nacional I purchased 

 a catalogue of the phaenogamous plants in the herbarium of the 

 museum, published in 1897 by the late Doctor Urbina. This work 

 has been of great assistance to me, but it contains the names of onl}?- 

 four cacti, all collected by Mr. C. G. Pringle. In the garden of the 

 museum there was a collection of living cacti, scarcely any of which 

 had been identified. I had the pleasure of meeting Don Manuel 

 Urbina, the son of the celebrated botanist, who kindly presented me 

 with a number of his father's botanical papers, including his mono- 

 graph on the peyote, published in the Anales del Museo Nacional, 

 volume 7, pages 25 to 48, 1900. 



To my great regret I was obliged to start northward without visit- 

 ing the wonderful cactus region of Tehuacan, in southern Puebla. 



On the way from Mexico City to San Luis Potosi I passed through 

 the country of the giant viznagas from which viznaga dulces are 

 made. Several species are used for this purj)ose, the principal one 

 being E chinocactus ingens. At several stations I saw specimens of 

 these great barrel-shaped or globular plants awaiting transportation. 

 They were in pairs, having been carried from the mountains on mule 

 back, one strapped on each side of the animal. The rigid penetrating 

 sj^ines had been removed before they were started on their way to 

 market, and consequently it was impossible to tell with certainty 

 to what species they belonged. 



At San Luis Potosi I found myself in the great tuna market. It 

 was winter and the only tunas on sale were the deep purple, or beet- 

 colored, tuna chaveiia, usually peeled ready for eating, and the acid 

 tuna xoconochtli, with a yellowish-pink rind, not eaten by itself but 

 used like lemons to season dishes which would otherwise be insipid. 

 One of the most important food staples in the market was the queso 

 de tuna, or " tuna cheese," usually made from the celebrated tuna 

 cardona, but sometimes also from tuna pachona, the latter being 

 easily distinguished by its deep red color, while the former is of a 

 88292— SM 1908 35 



