DESMIDIUM. 



[ 246 ] 



DLLPTOMUS. 



Sachs, Bot. 262; Notaris, Desmidiacee 

 ItalicTie, 1867: Delaporte, Desm. snhalp. 

 1877 (23 pis.). 



DESmD'IUM, Ag.— A genus of Desmi- 

 diacese. 



Char. Cells united into a brittle, regu- 

 larly twisted, triangular or quadrangular 

 filament, and two-toothed at the angles. 



The filaments exhibit one or two dark, 

 oblique, wavy lines, arising from their being 

 twisted. In the side view of the cells, the en- 

 dochi'ome exhibits thick,frequently cleft rays, 

 corresponding in number -nith the angles. 



D. Stvartzii (PI. 14. fig. 7; fig. 8, side 

 view of separate cell). Filament triangular. 

 Length ofjoint 1-2000 to 1-1660" ; breadth 

 of filament 1-630". Not uncommon. Spo- 

 rangia round or oblong. 



D. quadraiu/ulatum. Filaments quadran- 

 gular. Length of joint 1-2400" ; breadth 

 of filament 1-600 to 1-450". 



BiBL. Ralfs, Br. Desmid. 60; Kutzing, 

 Sp. Alfi. 190. 



DESMOGONIUM, Ehr.— A 



of 



Diatomacese. 



Char, Frustules those of Synedra united 

 into tablets, which are coherent by the angles. 



D. Eiitzinyii. Submarine marshes; Ger- 

 many. 



D. Gnjanense. Found in Asia, Africa, 

 and America. 



BrBL. Ehrenberg, Mih'og. ; Eabenhorst, 

 Flor. Ah/, i. 142. 



DEUtZ'IA, Thunberg.— A genus of Phi- 

 ladelphaceffi (Dicotyledonous Plants) re- 

 markable for the stellate hairs upon their 

 foliage (PL 28. fig. 26*), and the reticulated 

 membrane covering the seeds; both of which 

 structures form in- 

 teresting microsco- 

 pic objects. See 

 Haihs and Seeds, 



DIACAL'PE, 

 Bl. — A genus of 

 Cyathe8e(Polypodi- 

 aceous Fems), with 

 globular indusia, 

 splitting open at 

 the top(fig.l67), and 

 containing spo- 

 ranges inserted on a 

 punctiform recep- 

 tacle rising from 

 the middle of the 

 vein. Hei'baceous ; 

 leaves tripinnate, 

 membranous. Native of Java, &c. 



BiBL. Hooker, Sj/n. 45. 



Diacalpe asplenioides. 



Part of a pinnule with sori. 



Magnified 10 diams. 



DIACH^'A, Fries.— Age- Fig. 168. 

 nus of Myxomycetes, consist- 

 ing of perishable little plants, 

 growing over either living or 

 dead plants, with an elongated 

 membranous peridimu, wliich 

 falls oft' lilie a cap, and displays 

 a white reticidated capillitium 

 furnished with a floccose cen- 

 tral column, with interspersed 

 blackish-red spores. 



Diachcsa diners from Stemo- 

 nitis in the peridium, the colu- 

 mella, and the habit of growth. 



D. elegans, Fr. {Stemonitis, 

 Trentep.), the only species, 

 has been foimd in England, 

 upon the living leaves of the 

 Lily of the Valley &c. (fig. 

 168). 



BiBL. Fries, Syst. Mycol. 

 iii. 155; Berk. A7in. N. II. i. 



257 ; Corda, Ic. Fung. v. pi. 3. Diach^a elegans; 

 fig. 38. Magn. 25 diams. 



DIADES'MIS, Klitz.— A genus of Dia- 

 tomaceas (Cohort Naviculese). 



Char. Frustules navicular, closely united 

 into elongated biconvex filaments ; valves 

 with a median and terminal nodules. 

 Freshwater and marine. 



The markings have not been satisfactorily 

 investigated. 



D. confervacea (PI. 16. fig. 27). Breadth 

 of frustules (in front view) about half the 

 length; valves lanceolate, acuminate and 

 acute at the ends; length of frustules 

 1-960". 



Eight species, some fossil. 



BiBL. Kutzing, <S)j. ^?/7. 95; Rabenhorst, 

 Fhr. Alq. i. 259. 



DIAMOND-BEETLE. See Cubculio. 



DIAP'TOMUS, Westw.— A genus of 

 Entomostraca, of the order Copepoda, and 

 family Diaptomidae. 



Char. Head distinct from thorax; inferior 

 antennae two-branched ; thorax and abdo- 

 men each of five segments ; foot-j aws un- 

 branched ; legs five pairs, the first pair with 

 two branches, one three- the other two- 

 jointed; three succeeding pairs with each 

 branch three-jointed ; external ovary single, 

 large, lying across the abdomen. 



B. castor (PI. 20. fig. 38). Found in ponds 

 and slowly-running water ; common in spring 

 and autumn. Length about 1-8". 



BiBL. AVestwood, Eyitom. Text-hook ; 

 Baird, Br. Fntom', M.-Edwards, Crust, iii. 

 427. 



