with its large pale-blue heads, adds an unwonted brilliancy to the 

 clefts of dark basaltic rocks. Audibertia incana Benth. (No. 

 159) is conspicuous along the line of dry ravines, with its dense 



r, ■ , 



Other varieties include Lepidium Fremontii Watson, Hymenoded 

 salsola T. & G., Franseria dumosa Gray, Salazaria Mexicana 

 Torr., Lycium Torreyi Gray. 



Not least among the attractions of this flowering season are 

 the Cacti, which include Opuntia rutilla Nutt., presenting a 

 perfect mass of delicate pink rosettes, set in a bed of spines. 

 Cereus Engelmanni Parry exhibits flowers of a deeper purple 

 shade, which are succeeded by a delicious fruit, when it can be 

 safely extracted from its thorny envelope. MarnmiUaria pheh 

 osperma Engel., or " the fish-hook cactus," is found as a rarity in 

 rocky clefts, at this season adorned with its bright red fruit. On 

 all gravelly knolls in this section a common arborescent Opuntia 

 is met with (0. Echinocarpa Engel.). This species has an incon- 

 spicuous yellowish green flower nearly buried in a mass of barbed 

 spines ; otherwise its usually repulsive features are partly utilized. 

 by birds, who find in their spiny recesses, nesting places secure 

 from the attack of snakes. 



Chenopodiacem are everywhere largely represented by the fol- 

 lowing, viz., Atriplex expansa Watson, A. confertifolia Watson, 

 A. NuttdUii Watson, A. canescens Watson, Kochia Americana 

 Watson, Suoeda diffusa Watson, Eurotia lanata Moquin, and 

 Grayia polygalvides H. & A., the latter with much more graceful 

 foliage than noticed farther north, .almost reconciles one to the im- 

 position of this honored botanical name to a "grease wood." 



The undergrowth comprises quite a number of singular Cichora* 

 ceous Compositece, including Malacothrix Coulteri Gray, M. Torreyi 

 Gray, Rafinesquia Neo-Mexicana Gray, Calycoseris Wrbjlitil Gray. 

 Microseris macrochc'fa Gray, M. linenrijhltn Gray, ^t^haiwmeri" 

 Thurberi Gray, 8. exigua Nutt., Lygodesmia exigua Gray. To 

 these must be added as especially worthy of notice, the charming 

 Glyptopleura setulosa Gray (No. 129), with its pure white blossoms, 

 and cut fringed leaves, pressed close to the ground. This growing 

 abundantly everywhere on gravelly soil, or dry bottom land, pre- 

 sents a succession of flowers oiK'iiing in bright sunshine. Not un- 

 frequently on gravelly slopes we meet with the rare Composite 

 Monoptilon bellidiformis Gray (No. 100), heretofore only known 



