268 The Plant World. 



separate plants, and show, even in reproduction, by half-tone, 

 their striking differences. The lower one was neatly white in its 

 ground color, with triangular spots on the petals, which are 

 loose and barely touch one another when expanded. The 

 upper flower is purple, and the spot is broadly oval, while the 

 colors at the base are pencilled in a delicate manner. The third 

 flower is smaller, its petals overlap one another, the spots are 

 much longer than wide, and all the colors are more distinctly 

 outlined. 



The beauty of the species of Calochortus struck the early 

 Mexican inhabitants of California, and it is to them that we owe 

 the common name "Mariposa," which is to say "Butterfly." 

 Although they are now commonly known as "Mariposa lilies," 

 it requires but little botanical knowledge to recognize in the num- 

 ber of petals and the tunicated or coated bulb their closer re- 

 lationship to the tulips, from which they differ but little save 

 in the size and developm.ent of the petals and sepals. 



Soldiers' Home, California. 



EVAPORATION AND PLANT HABITATS IN JAMAICA. 



By Wm. H. Brown. 



With the increasing evidence that evaporation offers an 

 important criterion for comparing the climatic conditions of 

 plant habitats, it seems desirable to accumulate data on this 

 subject from as many regions as possible. An opportunity to 

 study, for a brief period, the evaporation rates with reference to 

 vegetation in the tropics was presented by the Johns Hopkins 

 University Botanical expedition of 1910 to Jamaica, under the 

 leadership of Prof. D. S. Johnson, upon which expedition it was 

 the writer's good fortune to be present. Besides obtaining some 

 information on the evaporation rates in two very different 

 tropical habitats, it was possible to observe the behavior of 

 Prof. Livingston's recently described non-rain-absorbing atmo- 

 meter in a region and season of frequent, though not exceedingly 

 heavy showers. 



The observations were continued for three weeks and four 

 days, beginning May 22, last, by means of the porous cup atmo- 

 meter of the common form * and also with the non-rain-absorb- 



•Livingston, B. E. A simple atmometer. Science. N.S. 28:319-20. 1908. 

 . Operation of the porous cup atmometer. Plant World, 13: 112-118. 1910. 



