dibl] 



GHje Ereagury at ISatattg, 



400 



are often so regular that the frustules 

 form admirable tests for ascertaining the 

 comparative merit of microscopes. 



Though Diatomacece are for the most 

 part free or only attached for a time, there 

 are a few genera in which an enormous 

 quantity of mucus is thrown out by the 

 frustules, which accordingly, as in Scliizo- 

 nema, Dickiea, &c, form variously shaped 

 filiform or alvoid fronds. In Cymbellece, a 

 suborder, the quantity of silex is compara- 

 tively so small that the plants are more 

 easily destructible than in the other sec- 

 tions. The peculiar motions in the genus 

 Bacillaria have been noticed above. In 

 many other genera motion has been ob- 

 served, but it is now well known that even 

 active motion is not incompatible with 

 the nature of vegetables. For full infor- 

 mation we refer to Mr. Smith's beautiful 

 work on Diatomacece. [M. J. B.] 



DIBLBMMA. The name of a Philippine 

 Island fern, in which the sori are of two 

 kinds : the first linear continuous, seated 

 on a submarginal receptacle ; the second 

 roundish or oblong, and irregularly scat- 

 tered. D. samarensis has simple fronds 

 and uniformly reticulated venation, short 

 free veinlets being included in the unequal 

 areoles. [T. M.] 



j DICALYX. The name given by Loureiro 

 to a few Asiatic bushes which were de- 

 scribed as belonging to the tea family. 

 Modern authors have shown, however, 

 that they are genuine species of Syjiplo- 

 cos : which see. [A. A. BJ 



DICELLA. A genus of Brazilian climb- 

 ing shrubs belonging to the Mulpighiacece. 

 The calyx has five segments each provided 

 with two glands at its base ; the petals are 

 stalked, unequal in size, and downy on the 

 outside ; the stamens are ten, united below 

 into a tube, the anthers hairy ; the ovary is 

 two-celled, surmounted by two hook-like 

 styles. Drupe woody, one-celled, one- 

 seeded. [M. T. M.] 



DICENTRA. A genus of Fumariacece, 

 the Bielytra or by mistake Bielytra of 

 some authors. They are known by the two 

 outer petals being spurred or bulging at 

 the base, the seeds crested, and the capsule 

 with two dry valves. The species are na- 

 tives of the Northern Hemisphere, and are 

 generally stemless herbs with ternately 

 compound leaves, and succulent stems 

 terminating in a raceme of large nodding 

 flowers, which are white, rose-coloured, or 

 purplish. The section Eucapnos has the 

 outer petals merely bulging at the base, 

 and the racemes compressed ; while Cucul- 

 laria has the outer petals produced back- 

 wards into two long spurs at the base, and 

 its racemes are simple. The two most com- 

 mon American species, which belong to the 

 second group, have white flowers. D. Ou- 

 cullaria is known in the United States as 

 Dutchman's Breeches, from the shape of 

 the spurred flower, and B. canadensis, 

 which is fragrant, as Squirrel Corn. A 

 stemless species from Virginia and North 

 Carolina, with rose-coloured flowers, B. 



formosa, is often cultivated in gardens; 

 but the best known and most beautiful is 

 B. spectabilis, from Northern China, which 

 has a leafy stem, and flowers nearly an inch 

 long, of a beautiful rose colour, with the 

 narrow constricted inner petals white; 

 the leaves are like those of the Moutan 

 peony in miniature. [J. T. SJ 



DICERANDRA. The name of a genus 

 belonging to the labiate order, chiefly dis- 

 tinguished from its congeners by the 

 presence of two straight and pointed ap- 

 pendages on the upper part of each sta- 

 men, hence the name, derived from Greek 

 words which together signify ' two-homed 

 stamens.' B. carolinensis is a small shrub, 

 a native of the United States, having erect 

 stems and narrow entire leaves. [G. D.] 



DICEROS. A name successively given by 

 different authors to species of Artanema, 

 Limnophila, and Vandellia. 



DICHJEA. A genus of orchids found 

 growing on tree stems in the West Indies 

 and the adjoining mainland. They are small 

 tufted plants having short erect or creep- 

 ing stems, thickly clad with small ovate- 

 oblong or linear leaves arranged in a two- 

 ranked manner, and solitary inconspicuous 

 axillary greenish flowers. About a dozen 

 species are known. [A. A. B.] 



DICH^ETA. A genus of small annual 

 Californian composite herbs, of which two 

 species are known. They seldom exceed 

 six inches in height, and are found on the 

 margins of pools or in wet places. The 

 stems and leaves are covered when young 

 with loose white wool. The lower leaves 

 are generally pinnatifld with linear seg- 

 ments, and the upper entire; and the 

 yellow flower-heads are single on the ends 

 of the stems. The genus is nearly allied 

 to Burrielia, but differs in the pappus be- 

 ing composed of from four to eight ob- 

 long-obtuse scales, with generally two 

 which are awl-shaped and awned. [A.A.B.] 



DICHASIUM. A name once given to an 

 Indian fern which proves to be the same as 

 the English Lastrea Filix-mas paleacea. 



DICHERANTHUS. A genus of niece- 

 bracece allied to Pterantlms. Small shrubs 

 from the Canary Islands, with opposite or 

 verticillate fleshy linear-cylindrical leaves, 

 dilated and clasping at the base ; and 

 flowers in small dense compound corym- 

 bose cymes at the apex of the branches ; 

 calyx segments mucronate, hooked when 

 in fruit ; corolla none. [J. T. S.] 



DICHILUS. A genus of slender erect 

 or prostrate South African leguminous 

 herbs, nearly related to Argyrolubium, 

 but differing in the keeled petal being 

 rather longer than the vexillum, and in 

 the pods being swollen at intervals (tor- 

 ulose), not flat, and clad with silky hairs. 

 The stalked leaves are made up of three 

 narrow leaflets. The little yellow flowers 

 are either solitary or racemed in the axils 

 of the leaves, their calyx distinctly two- 

 lipped, and the pod is smooth, narrow, an 



