II CUCURBITACEiE — CRASSULACE.E 195 



ultraviolet rays, which, as I have shown elsewhere,' 

 are visible to some insects. In support of this view 

 he finds that they act energetically on photographic 

 plates. The fruit is a globular berry with flat, nearly 

 orbicular seeds. 



CEASSULACE^- 



Generally succulent plants with numerous small 

 regular flowers, with usually 5 or sometimes more 

 sepals, petals, and carpels, and the same number of, 

 or twice as many, stamens. They generally have honey, 

 which is secreted by glands at the base of the ovary. 



TlLL^A 



T. muscosa is probably self-fertilised. 



COTYLEPON 



C. Umbilicus, Pennywort, so called from the thick, 

 round, peltate leaves. The flowers are protandrous. 

 The only insects recorded as visiting this species belong 

 to the genus Thrips. They do not probably, however, 

 serve to fertilise the flowers. The plants grow on almost 

 bare rocks and walls, especially on our western coasts. 



Sedum 



We have nine species of this genus. Two have flat 

 broad leaves, one {S. Rhodiola) with 4 sepals and petals, 

 the other [S. Telephium) with 5. The other species 

 have leaves as thick, or almost as thick, as they are broad. 

 Four have white or reddish flowers ; of these, two have 

 ovoid or globular leaves, one of which '{S. anglicum) 

 is glabrous, the other [S. dasy'pliyllum) with a few 

 glandular hairs on the calyx and pedicels ; the other 

 two have oblong or cylindrical leaves ; one [S. album) 

 is glabrous, the other [S. villosum) is viscidly downy 



' Avebury (Lubbock), Ants, Bees, and Wasps. 



