D1CTYOCYSTA. 



[ 260 ] 



DICTYOTACE^E. 



of a single piece ; hence they are not Diato- 

 maceae. This piece is siliceous and loosely 

 reticulate or stellate. Marine and fossil. 



Kiitzing enumerates twenty-nine spe- 

 cies ; distinguished principally by the num- 

 ber of external spines and internal are- 

 olse ; they vary in diameter from 1-1150 

 to 1-370". 



D. gracilis (PI. 25. fig. 19, perspective 

 view; 20, side view; 21, view from above). 



D. fibula (PL 51. fig. 5). 



BIBL. Ehrenberg, Berl. Abh. 1838, and 

 Mikrog. ; Kiitzing, Bacill. and Sp. Alg. 142 ; 

 Pritchard, Inf. 735. 



DICTYOCYS'TA, Ehr. A genus of 

 Peritrichous Infusoria. 



Char. Free ; enclosed in siliceous per- 

 forated or pitted loricae, with an anterior 

 fringe of long cilia, and an inner circle of 

 uncini ; surface smooth. 6 species. Marine. 

 (Kent, Inf. 624,) 



DICT^OLAMPRA, Ehr. A genus of 

 Diatomacese. 



Char. Frustules single ; no internal septa ; 

 valves equal, cellular (apparently) in the 

 middle, the smooth margin radiate. 



D. stetta (PI. 18. fig. 68). The only spe- 

 cies. Found among Polycystina from Bar- 

 badoes. 



BIBL. Ehr. Ber. Berl Akad. 1847, 64. 



DICTYOP'TERIS, Presl. A genus of 

 Polypodiaceous Ferns, deriving their name 

 from the reticulated arrangement of the 

 veins, = Polypodium, pt. 



DICTYOPYX'IS, Ehr., Grev. A genus 

 of marine Diatomaceae. 



Char. Frustules areolar, united into short 

 bands ; valves convex, cupuliform, hoop 

 absent, = Pyxidicula, pt. 



D. brevis, Grev. ; I), cruciata, Ehr. 



BIBL. Grev. Mic. Jn. 1862, 22 (fig.); 

 "Ebx.Berl.Ahk. 1844; Pritchard, /w/825; 

 Rabenhorst, Fl Alg. i. 36. 



DICTYOSI'PHON, Grev. A genus of 

 Dictyosiphonaceae (Fucoid Algae), repre- 

 sented in Britain by a common branched 

 filamentous sea- weed (D. faniculaceus), 

 with the frond growing from one to several 

 feet long, of an olive or rusty-brown co- 

 lour. The fructification at present known 

 consists of ovoid sporanges, imbedded in 

 the cellular tissue of the branches, lying 

 lengthways; they open by a pore at the 

 surface. 



BIBL. Harvey, Mar. Alg. 40, pi. 7 D ; 

 Greville, Alg. Brit. pi. 8 ; Thuret, Ann. Sc. 

 Nat. 3 ser. xiv. 238. 



DICTYOSIPHONA'CE^E. A family 



of Fucoideae. Olive-coloured sea-weeds 

 with cylindrical branched fronds, the oospo- 

 ranges imbedded lengthways in the sub- 

 stance of the frond, opening by a pore on, 

 the surface. 



British Genera. 



Dictyosiphon. Root a minute naked 

 disk ; frond cylindrical, branched ; oospo- 

 ranges scattered irregularly, solitary or in 

 dot-like sori. 



Striaria. Root a minute naked disk ; 

 frond cylindical, branched; oosporanges 

 arranged in transverse lines on the surface 

 of the frond. 



BIBL. See the genera. 



DICT YOSPH^E'RIUM, Nag. A genus 

 of Palmellaceous Algae. 



Char. Cells oblong, green, connected by 

 filaments, united into free, rounded, plate- 

 like layers. Freshwater. 



2 species. D. Ehrenbergii (PI. 3. fig. 11). 



BIBL. Nageli, Einzell. Alg. 73 ; Archer, 

 Qu. Mic. Jn. 1866, 127. 



DIOTYOSPOR'IUM, Corda. A genus 

 of Torulacei (Coniomycetous Fungi) con- 

 taining one species, D. ele- 

 gans (fig. 172), a minute Fig. 172. 

 fungus growing upon oak 

 which has been stripped of 

 its bark ; very remarkable 

 for the reticulated charac- 1 

 ter of its spores. 



BIBL. Berk. & Br. Ann. 

 Nat. Hist. 2 ser. v. 460 ; 

 Corda, Icon. Fung. ii. pi. 8. 

 fig. 29. 



DICTYO'TA, Lamx. A genus of Dic- 

 tyotaceae (Fucoid Algae), containing one 

 British species, D. dichotoma (PI. 4. 

 fig. 2), common between tide-marks, on 

 rocks, &C.J remarkable for itsdichotomously 

 divided membranous frond, of olive-green 

 colour, 3 to 12" long, which, on distinct 

 individuals, produces three kinds of re- 

 productive organs, viz. \.tetraspores, divided 

 crucially, and either scattered or arranged 

 in sori ; 2. spores grouped in sori and covered 

 by the common epidermis of the thallus ; 

 and 3. antheridia, in patches on either face 

 of the thallus. 



BIBL. Harvey. Brit, Alg. 39, pi. 7A; Phyc. 

 Brit. pi. 103 ; Greville, Alg. Brit. pi. 10 ; 

 Thuret, Ann. Sc. Nat. 4 se"r. iii. 7, pi. 2. 



DICTYOTA'CE^E. A family of Fucoi- 

 deae. Olive-coloured inarticulate sea- weeds, 

 with large spores like those of Fucaceas, 

 superficial, in definite spots or lines (sori), 



Dictyosporium 



elegans. 



Spores magnified 

 1000 diameters. 



