CACTACE^ OF MEXICO- — SAFFORD. 533 



The latter species is an interesting cylindrical Opuntia belonging to 

 the series Clavatse, in which the spines are not sheathed in scabbards. 

 Another species of this group is puntia Jjidhispitia, from Perros 

 Bravos, north of Parras, where it was collected by Doctor Gregg in 

 1848. Its flowers and fruit have never been described. 



In addition to the cacti, there were several other xerophytes ; among 

 them an agave with remarkably short and broad leaves, called " noa," 

 from a locality 18 miles east of Parras, on the road to Mezquite ; a 

 very narrow and rigid leaved agave, called " palmillo," from the Bar- 

 ranca de Llanitos, 9 miles east of Parras ; and a species of Dasylirion, 

 called "• sotol," the crowns of which are nsed, like those of an agave, 

 for making a fermented drink. 



At Aguascalientes I collected several sheath-spined Opuntias, in- 

 cluding the coyonostli (Opuntia imhricata) and the low clavellina 

 {Opuntia tunicata) (pi. 10, fig. 5). Of the latter species my guide 

 seemed to have a horror. He would repeatedly warn me : '' Be careful, 

 Seiior; do not touch it; it is muy hravo, a plant of the devil." And, 

 indeed, it seemed fairly to leap in eagerness to sink its barbed spines 

 into the flesh of the unwary passer-by. The spines are easily with- 

 drawn, but the barbed scabbards remain to fester, and can only 

 be extracted with difficulty. On the hills above the hot springs at 

 Aguascalientes I found only two other cacti. One, Mamillaria un- 

 cinata, was a low flat-topped species growing among the grass, with 

 a single stout claw-shaped central spine, surrounded by a number of 

 radials, and with white petals, bearing a median stripe of jiink. The 

 other was an Echinocactus to which I have already referred {Echhio- 

 eactus crispatusf) (pi. 4, fig. 5), closely related to E. multicostatus^ 

 but Avith many broad, sword-shaped spines converging about the 

 apex and almost concealing the flower. 



At Guadalajara I had the pleasure of meeting Dr, Adrian Puga, 

 to whom I am indebted for many courtesies. Through his kindness 

 I obtained specimens of at least two species of Pereskiopsis, cacti 

 related to the Opuntias, but resembling the genus Pereskia in having 

 well developed leaves (pi. 10, fig. 2). One of these species, Pereskiop- 

 sis aqnosa^ bears edible watery fruit called " tunas de agua." Another 

 interesting plant was a Nopalea (i3robably Nopalea karwinskiana) 

 with beautiful rose-colored flowers, locally known as " nopalillo de 

 for.'"' In Nopalea, an Opuntia-like genus including the plant upon 

 which the cochineal insect is reared, the floral leaves are erect, instead 

 of spreading as in Opuntia, and the stamens are longer than the 

 perianth but shorter than the style (see fig. 14, p. 549). In the gar- 

 dens of Guadalajara several species of climbing triangular Cerei are 

 cultivated, all of which bear edible fruit called " pitahayas." One 

 species has recently been described as new under the name Cere us 

 tricostatus (pi. 6, fig. 1). In addition to these I noticed a columnar 



