DICTYOCYSTA. 



[ 260 ] 



DICTYOTACE^. 



of a single piece ; hence they are not Diato- 

 macese. 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- 

 olae ; they vary in diameter from l-lloO 

 to 1-370". 



D. yracilis (PI. 2.5. fig. 19, perspective 

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



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



BiBL. Ehrenberg, Berl Ahh. 1838, and 

 Mikroij. ; Kiitzing, Bacill. and Sp. Aly. 142 ; 

 Pritchard, Inf. 735. 



DIUTYOCYS'TA, Ehr. — A genus of 

 Peritrichous Infusoria. 



Cliar. Free ; enclosed in siliceous per- 

 forated or pitted loricse, with an anterior 

 fringe of long cilia, and an inner circle of 

 uncini ; surface smooth. 6 species. Marine. 

 (Kent, Itif. 024.) 



DICTY'OLAMPRA, Ehr.— A genus of 

 Diatomaceae. 



( 'Jtar. Frustules single ; no internal septa ; 

 valves equal, cellular (apparently) in the 

 middle, the smooth margin radiate. 



D. Stella (PL 18. fig. 68). The only spe- 

 cies. Found among Polycystina from Bar- 

 badoes. 



BiBL. Ehr. Ber. Berl Alcad. 1847,54. 



DICTYOP'TERIS, PresL— A genus of 

 Polypodiaceous Ferns, deriving their name 

 from the reticulated arrangement of the 

 veins, =^ Pulypodium, pt. 



DICTYOPYXIS, Ehr., Grev.— A genus 

 of marine Diatomacejie. 



Char. Frustules areolar, united into short 

 bands ; valves convex, cupuliform, hoop 

 ahuent, = Py.ridicula, pt. 



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



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

 'Ehx. Berl. Ahh. 1844; Pritchard, /»/.825; 

 IJabenhorst, Fl. Ah/, i. 36. 



DICTY^OSI'PIION, Grev.— A genus of 

 Dictyosiphonacete (Fucoid Algae), repre- 

 sented in Britiiin by a common brauclied 

 filamentous sea-weed (-D. faniculaceus), 

 with the frond growing from one to several 

 feet lonjT, of an olive or rustv-brown co- 

 lour. The fructilication at present known 

 consists of ovoid sporanges, imbedded in 

 the cellular tissue of the branches, lying 

 lengthways ; tliey open by a pore at the 

 surface. 



BiBL. Harvey, Mar. Aly. 40, pi. 7 D ; 

 Greville, Air/. Brit. pi. 8 ; Thuret, Ann. Sc. 

 Nat. 3 ser. xiv. 2-38. 



DICTYOSlPIlONA'CE.aE.— A familv 



of Eucoideae. Olive-coloured sea-"weeda 

 with cylindrical branched fronds, the oospo- 

 ranyes 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- 

 rattyes scattered irregidai-ly, solitary or in 

 dot-like sori. 



Striaria. Root a minute naked disk ; 

 frond cylindical, branched ; oosporaiiyes 

 arranged in transverse lines on the sm-face 

 of the frond. 



BiBL. See the genera. 



DICTYOSPn.E'RIUM, Nag.— A genus 

 of Palmellaceous Algae. 



Char. CeUs oblong, green, connected by 

 filaments, united into free, rounded, plate- 

 like layers. Freshwater. 



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



BiBL. Niigeli, Einzell. Aly. 73 ; Archer, 

 Qu. Mic. Jn. 1866, 127. 



DIOTYOSPOR'IUxM, Corda.— A genus 

 of Torulacei (Coniomycetous Fungi) con- 

 taining one species, D. ele- 

 yans (fig. 172), a minute 

 fungus growing upon oak 

 which has been stripped of 

 its bark ; very remarkable 

 for the reticulated charac- 

 ter of its spores. Diotyosporium 



BiBL. Berk. & Br. Ann. elegans. 



Nat. Hist. 2 sef. v. 460 ; Spm-es magnified 

 „ , T „ . . , _" lOUO diameters. 



Uorda, Ico7i. rioiy. ii. pi. 8. 

 fig. 29. 



DICTY'O'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. ; remarkable for its dichotomously 

 divided membranous frond, of olive-green 

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

 individuals, produces three kinds of re- 

 productive organs, viz. l.tefraspores, 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. Harvev. Brit. Ah/. .39, pi. 7A; Phyc. 

 Brit. pi. 103 ; 'Greville, \ily. Brit. pi. 10 ; 

 Thuret, Ann. Sc. Nat. 4 ser. iii. 7, pi. 2. 



DICTYOTA'CE.E.— A family of Fucoi- 

 dea3. Olive-coloured inarticulate sea-weeds, 

 with ItiY^e spores like those of Fucacea?, 

 superficial, in definite spots or lines (sori), 



