DESMIDIUM, 



246 ] 



DIAPTOMUS, 



Sachs, Sot. 262; Notaris, Desmidiacee 

 Italiche, 1867; Delaporte, Desm. siibatp. 

 1877 (23 pis.). 



DESMID'IUM, Ag. A genus of Desmi- 

 diaceae. 



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- 

 dochrome exhibits thick,fre<juently cleft rays, 

 corresponding in number with the angles. 



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

 view of separate cell). Filament triangular. 

 Length of joint 1-2000 to 1-1660" ; breadth 

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

 rangia round or oblong. 



D. quadrangulatum. Filaments quadran- 

 gular. Length of joint 1-2400"; breadth 

 of filament 1-600 to 1-450". 



BIBL. Ralfs, Br. Desmid. 60; Kiitzing, 

 Sp. Alg. 190. 



DESMOGONIUM, Ehr. A genus of 

 DiatomaceaB. 



Char. Frustules those of Synedra united 

 into tablets, which are coherent by the angles. 



D. Kutzingii. Submarine marshes; Ger- 

 many. 



D. Gujanense. Found in Asia, Africa, 

 and America. 



BIBL. Ehrenberg, Mikrog. ; Rabenhorst, 

 Flor. Alg. i. 142. 



DEUTZ'IA, Thunberg. A genus of Phi- 

 ladelphaceee (Dicotyledonous Plants) re- 

 markable for the stellate hairs upon their 

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

 membrane covering the seeds; both of which 

 structures form in- 

 teresting microsco- Fig. 167. 

 pic objects. See 

 HAIRS and SEEDS. 



DIACAL'PE, 

 Bl. A genus of 

 Cyatheae(Polypodi- 

 aceous Ferns), with 

 globular indusia, 

 splitting open at 

 thetop(fig,167),and 

 containing spo- 

 ranges inserted on a 

 punctiform recep- 

 tacle rising from 

 the middle of the 

 vein. Herbaceous ; 

 leaves tripinnate, 

 membranous. Native of Java, &c. 



BIBL. Hooker, Syn. 45. 



Diaealpe asplenioides. 



Part of a pinnule with sori. 



Magnified 10 diams. 



DIACH^E'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 peridium, which 

 falls oft' like a cap, and displays 

 a white reticulated capillitium 

 furnished with a floccose cen- 

 tral column, with interspersed 

 blackish-red spores. 



Diachcea 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 found in England, 

 upon the living leaves of the 

 Lily of the Valley &c. (fig. 

 168). 



BIBL. Fries, Syst. Mycol. 

 iii. 155; Berk. Ann. N. H. i. 



257 ; Corda, Ic. Fung. V. pi. 3. Diacheea elegans; 

 fig. 38. Magn. 25 diama. 



DIADES'MIS, Kiitz. A genus of Dia- 

 tomaceaa (Cohort Naviculeae). 



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. Kiitzing, Sp. Alg. 95; Rabenhorst, 

 Flor. Alg. 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-jaws 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. 



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

 and slowly-running water; common in spring 

 and autumn. Length about 1-8". 



BIBL. Westwood, Entom. Text-book-, 

 Baird, Br. Entom ; M.-Edwards, Crust, iii. 

 427. 



