405 



Kfyz CreaSurp at 230tanj). 



The development of the frond is curious, 

 each division ending in a ' single cell by 

 the constant division of which at its lower 

 side the other cells of the frond are form- 

 ed, the terminal cell being then continu- 

 ally pushed onwards.' This is the same 

 mode of growth as that which obtains in 

 exogenous stems. [M. J. BJ 



DICTYOTE.3E. An order of dark-seeded 

 Algce with superficial spores or cysts, dis- 

 posed in definite spots or lines. The 

 fronds are sometimes flat, sometimes 

 thread-like, and occasionally branched and 

 tubular. In Hydroclathrus it is pierced 

 with large holes. Some beautiful Algce, as 

 Padina,Zonaria, Haliseris, belong to this 

 order, which has representatives in every 

 part of the world, but very few are found 

 in high latitudes. Padina pavonia, the 

 turkey feather laver, is common in warm 

 countries, but extends to our own coasts 

 as far as lat. 51°, though in North America 

 it does not pass farther than lat. 25°. In 

 Cutleria there is reason to believe that 

 true spermatozoids are produced ; but in 

 some other genera, as Stelophura, two kinds 

 of fruit occur, the one of which produces 

 large, the other small zoospores, both of 

 wh ich have lash-like appendages. The cysts, 

 which produce the large zoospores, are 

 called Trichosporangia ; those which pro- 

 duce the smaller, Oosporangia. [M. J. B.] 



I DICTYOXIPHIUM. A genus of poly- 



i podiaceous ferns related to Lindscea, from 

 which it is distinguished in the first place 



I by its compoundly-reticulated veins hav- 

 ing free included .veinlets in their areoles ; 



'. and in the second, by its indusium exceed- 

 ing and being inflected over the margin of 



, the frond. The fronds are simple, nar- 

 rower in the fertile parts, and the sori are 



I linear continuous and marginal, with the 

 indusium opening outwardly. There are 

 only a couple of species, which are found 

 in Panama and New Grenada. [T. MJ 



DICYPELLITTM. The name of a Bra- 

 zilian tree of the laurel family. The flowers 

 are dioecious. The male 'flowers are not 

 described, but the female ones have a 

 six-parted perianth ; twelve barren sta- 

 mens in four rows, the outermost petal- 

 like, the innermost small and scale-like, 

 the intermediate ones glandular. The 

 fruit consists of a one-seeded berry, sur- 

 j rounded by the thickened fleshy perianth, 

 ; which, with the sterile stamens, is per- 

 : sistent. The bark of D. caryophyllatum 

 \ furnishes Clove Cassia. [M. T. M.] 



I DICYRTA A genus of Gesneraeece, con- 

 | taining a single species, a native of Guate- 

 ( mala. It is a perennial stoloniferous 

 j herb, with opposite leaves on long petioles, 

 j and solitary axillary flowers, the small co- 

 rollas of which have a slightly-curved 

 tube and an equally flve-lobed limb. There 

 j are four didynamous stamens, with the 

 rudiment of a fifth, inserted at the base of 

 the tube. The disk is fleshy five-sided ; the 

 stigma capitate, depressed. [W. C] 



DIDER.MA A genus of myxogastrous 



Fungi, characterised by a double peridium. 

 of which the outer is quite smooth and 

 crustaceous ; the inner delicate and at- 

 tached to the straggling hairs amongst 

 which the spores are seated. In some 

 species the peridium bursts by regular ra- 

 diating fissures, so as to look like a little 

 flower, while in others it is ruptured ir- 

 regularly. One of the most common spe- 

 cies, D. vernicosmn, is characterised by its 

 obovate shining chestnut-coloured outer 

 peridium. It is common in woods, on 

 mosses, twigs, &c, and is often very con- 

 spicuous. The flower-like species are by 

 no means common. The genus is found 

 more or less frequently in all temperate re- 

 gions. [M. J. B.] 



DIDICLIS. Selaginella. 



DIDISCCS. A genus of umbellifers, 

 characterised by the fruit being very 

 mucft flattened laterally, each half with 

 five ridges, the middle ridge most promi- 

 nent. The name of this genus is intended 

 to indicate the double disk-like fruit. The 

 species are herbaceous and natives of Aus- 

 tralia. D. cceruleus is a showy plant, cover- 

 ed with hairs ; its leaves three-parted, 

 each division again subdivided ; its flowers 

 blue. The fruit when mature is covered 

 with small tubercles. Another species, D. 

 albiflorus, has no hairs, and the flowers are 

 I white. [G. D.] 



I DIDISMUS. A genus of Cruciferce, with 

 pods breaking across into joints which 

 have one or two seeds in each, the upper- 

 . most joint ending in a striated beak, the 

 p lower one truncate at the apex. Flowers 

 i white or yellow. The species occur in 

 Greece, Syria, and N. Africa. [J. T. S.] 



DIDYMIUM. A genus of myxogastrous 

 Fungi, distinguished by the outer coat of 

 the peridium being scurfy, mealy, scaly, 

 tomentose, &c, and bursting irregularly. 

 The species are numerous and sometimes 

 beautiful. One of the most common is B. 

 cinereum, which occurs everywhere, and 

 is easily known by its stemless cinereous 

 peridium, and the snow-white flattish hairs 

 amongst which the dark spores are dis- 

 persed. The genus belongs essentially to 

 temperate climates. [M. J. B.] 



DIDYMOCARPUS. A genus of Cyrtan- 

 drcccece, containing fully thirty species, na- 

 tives of India. They are caulescent or 

 stemless herbs or undershrubs, with the 

 leaves serrate or crenate petiolate, those on 

 the stem being opposite or rarely alternate; 

 the flowers blue or white, in cymes ; the 

 calyx five-cleft; and the corolla funnel- 

 shaped and unequally five-lobed. There 

 are four stamens, two of which only are 

 generally fertile; the long capsule bursts 

 longitudinally, and contains many naked 

 sessile pendulous seeds. [W. C] 



DIDYMOCHITON. A genus of Meliacece, 

 consisting of trees or shrubs, natives of 

 the Moluccas. They have soft compound 

 leaves, and flowers in axillary spikes or 

 heads. The corolla has five linear petals, 

 attached below to the tube of the stamens, 



