A. Anchoring roots and bases of some lateral roots of Carnegiea gigan- 

 tea, 6.8 m. high, from the bajada near West Wash. 



B. Tap-root and secondary roots making up the anchoring system and 

 the bases of some of the superficial roots of a specimen of Carnegiea, 1.2 m. 

 high, from same habitat as the cactus shown in A. 



C. Tap-root and bases of laterals of Parkinsonia microphylla which was 

 growing near Carnegiea shown in B, and which appears in plate 14. 



