ERYSirHE. 



[ 303 ] 



EUACTIS. 



Podo^phrrrid. Tlio TTawthorn-bliii'lit and 

 the rium-blijrlit bi'luiii^- to this division, 



SpJuerotheca. The Hose-mildew, E. pan- 

 nnm, auct., belong-s to this proup, and is 

 di.stin<ruislied from E. maculan'x, ^\'alh•. 

 (S. Casfaipici, .T. lit? v.), the Ilop-mildew, by 

 the appeudicles of the former beinp; white, 

 whik^ those of the latter are cohiured. The 

 mycelium of the rose-mildew seems to be 

 the same tiling as Oidium leucocunium, Desm. 

 The similar structure of the Ilop-mildew 

 has been described and figured (from Dr. 

 Plondey's drawings) in the Trans, of the 

 Horticultural Society. He was the first to 

 discover the conversion of one of the oidioid 

 cells into pycnidia. 



Phi/Uactima. E. fpiffatn, Schlecht., com- 

 mon on the hazel and other trees and large 

 shrubs, is dislinguislied from the other 

 forms of Phi/Udctinia by having a bulbous 

 base to its appeudicles, which contain 2 to 

 4 sporidia. 



T'ncinula. E. odiinca, Schlecht., is re- 

 ferred here ; its distinctive character is the 

 existence of the hooked appendicles. Found 

 on willows. E. bicornis, Lk., occurring 

 upon maples i^'C, has eight spores. 



31icrosphcpna. E. lienicillata, occm'ring 

 on Vibnnnnn Opnlus, &c. Several species 

 occur in this country, of which one of the 

 best-known is M. penicillata. The charac- 

 ters of the appendicles, which are dichoto- 

 mously branched at the tip, are the same as 

 those of Podosp/tceria ; but there are many 

 asci, instead of one only. 



Erysiphe. E. I'm, Grey., is E. Martii 

 of LeveiUe, distinguished by its globose, 

 many-spored asci and the simple or irre- 

 gularly branched appendicles. E. tortilis, 

 Lk., has coloured appendicles ten or more 

 times the length of the conceptacle. It 

 grows on Cormts sancpdnea, the Dogwood 

 tree. E. communis, Lev., is not x-eiy well 

 ch.aracterized ; it has coloured appendicles, 

 which are only twice or thrice as long as 

 the conceptacle ; the asci vary from four to 

 eight, as do also the spores contained in 

 each. This species grows on a great variety 

 of herbaceous plants, Eanunculacese, Com- 

 positae, Leguminosaj, Cruciferse, Polygo- 

 nacere, &c. 



Perhaps a doubt might be admitted whe- 

 ther the above subdivisions really represent 

 more than six species of this genus. 



BiBL. Lt5veille, Ann. Sc. ^at. 3 ser. xv. 

 ion, pis. G-1 1 ; Berk., Hook. Br. El. ii. pt. 2. 

 325; Tr. Ilort. Soc. London, ix. Gl ; Greville, 

 Sc. Crypt. Fl. pis. 134, 164. figs. 2, 29G : 



Tulasne, Compt. Pendus, 18-'53; Ann. Sc. Nat. 

 4 ser. vi. 299, and C'arpoloipa, i. 18G0; Cooke, 

 Handbook, 645 ; Taylor,' M. M. Jn. 1875, 

 xiii. 121 ; De Bary and Woronin, Peit. z. 

 Morph. 1870; Sachs, Pot. 312. 



See also Oidium. 



EliYTHR.E'US, Duges.— See Anystis. 



ESCHAR'lDyE.— A family of Cheilosto- 

 matous Polyzoa ; containing the genera 

 Lepralia, Unibonula, Porella, Escharoidcs, 

 Smittia, Phylactella, MucroneUa, Palmicel- 

 laria, and Retepora. 



ESCHAROl'DES, Smitt.— A genus of 

 Cheilostomatous Polyzoa, fam. Escharidae. 



2 species ; deep water. (Hincks, Polyzoa, 

 336.) 



ESPAR'TO.— The bast-fibres of a ^rass, 

 Lyyeimi spartum {Stipa tenacissima, Linn. ; 

 Makrochloa, Kunth), a coarse fibrous ma- 

 terial, extensively used in the manufacture 

 of paper. The fibres are shorter than those 

 of most allied substances : and the epider- 

 mic wavy margined cells are so short as to 

 render the distinction of this material toler- 

 ably easy. 



It occm*s extensively in the south of Eu- 

 rope, in North America, and in the centre 

 and south of Spain. 



BiBL. Henfrey-Masters,5o^.400; Wiesner, 

 Techn. Mikr. 225 (fig.). 



ESTHE'RIA, Rlippell and Straus-Diirck- 

 heim (Cyzicus, Audouin ; Isatira, Joly). 



A bivalved phyllopodous Entomostracon, 

 having 24 pairs of foliaceous limbs, and 

 ovate valves, horny, delicate, concentrically 

 ridged, bearing from 7 to 80 lines of growth, 

 with intermediate reticidation or other 

 sculpturing. 



2G species are known, from fresh and 

 brackish waters of warm climates ; and 

 more than 20 fossil, Devonian to Tertiary. 



BiBL. Baird, Zool. Proc. 1849, 87; 1852, 

 30 ; 1859, 232 ; 1860, 188 and 392 ; Rupert 

 Jones, Fuss. Estherice {Pal. Soc), 1862 ; E. 

 Grube, ^rc7?./. Naturgesch. 1853, xix., and 

 1865, xxxi. 



EUACTIS, Kiitz.— A genus of Oscillato- 

 riaceaj (Confervoid A]ga3), of the tribe Rivxi- 

 lariese, consisting of little, hard, solid, elastic, 

 mostly hemispherical bodies, from 1-2 to 2'" 

 in diameter, growing upon stones in the sea 

 or rivers, &c. ; concentrically zoned, com- 

 posed of radiating, flagelliform, repeatedly 

 sheathed filaments, the sheaths of which are 

 open and slit above (PI. 8. fig. 16), but con- 

 nected together side by side, so as to form 

 a tough gelatinous mass, not becoming in- 

 crusted "with carbonate of lime. To this 



