PEETGONIMUS. 



[ 



PERISPOEIUM. 



PERIGON'IMUS, Sars.— A genus of 

 AtractylidiV (ITydiMid Zoopliytes). 



DiiR'vs Iroiu Atractylis in the simple fixed 

 spove-sacs being medusiforni. 



On other marine zoophytes, shells, &c. 



Biiii,. St. \\'ri!,'lit, rr. Boy. Sor. Edin. 

 1S57, 18^58; Ann. N. II. 1801, 1;J0; Alder, 

 Trans. Ti/nes. F. C. v. 230 ; AUman, Ann. 

 N. IT. 1863,1804; Hincks, Ili/d. Zooph. S9. 



P]':rtrOLA, Fries.-i'. Ummdosa, Fr., 

 described as a Sclerotioid Fur,o:us, is an 

 obscure, irregular, tleshy body, with a white 

 villous surface, foimd growing on potatoes. 

 It is probably the early form of some unas- 

 certained species of fungus. This was cha- 

 racteristic of those forms of potato-rot 

 which were known before the introduction 

 of tlie Peronospora. 



PEPtlP'TERA, Ehr.— A genus of Dia- 

 tomaceoe. 



Char. Frustules single, compressed ; valves 

 dissimilar, one being simply turgid, the 

 otlier winged or furnished with horns ; 

 horns sometimes branched and attached to 

 the extreme margin. Fossil. 



Valves not areolar nor punctate under 

 ordinary illumination. America and Ber- 

 muda. 



P. cMaymdophora (PL 50. fig. 41) ; P. te- 

 tracladia (W. 18. fig. 6G) ; P. capra (PL 18. 

 fig. 07). 



BiBL. Ehrenb. Ber. Berl. Ak. 1844, 263 ; 

 Kiitz. Sp. Alq. 25. 



PEPtlSPIRA, St.— A genus of Holotri- 

 chous Infusoria. Free, ovate; mouth an- 

 terior ; oral cilia extending spirally towards 

 the posterior end. 



P. ovum ; green, = Iloplophryu ovum ? 

 (Kent, /«/". 511.) 



PERISPOPJA'CEL— A famil}; of Asco- 

 mycetous Fungi, mostly epiph}i;ic and of 

 smaU size, characterized by producing floc- 

 cose commdn receptacles (mostly) radiating 

 from a point, forming patches upon leaves, 

 Sec, in the centre of which are developed 

 somewhat globular perithecia of obscure 

 cellular structure, persistent, bursting at 

 the summit, filled densely with subgelatin- 

 ous, scarcely diftluent gelatine ; sporidia 

 produced in asci, subsequently often eff"used, 

 simple, free, and mixed with the gelatine 

 in the centre of the peritheciuiu. The m}'- 

 celia of these plants, bearing conidial struc- 

 tures, have been described as distinct fungi, 

 for example those of Erysiphe as Oidia, 

 &c. See Eeysiphe. Eitiotium probably 

 belongs here. British Genera : 



Lasiobotrys. Perithecium fleshy-horny. 



globular, naked, collapsing at the sum- 

 mit. 



Capnodium. Perithecium fleshy, clavate, 

 double (the outer cellular, interior hya- 

 line), mucilaginous, opening by a fringed 

 mouth ; asci containing about six spores in 

 two rows. 



Erysiphe. Perithecium membranous, 

 closed at first, afterwards open, supported 

 on a persistent radiating mycelium formed 

 of continuous filaments bifid at their ends. 

 Asci one to eight, paraphyses none ; spores 

 definite, ovate. 



Pcrisporium. Perithecium superficial, 

 at length bursting irregularly. Asci club- 

 shaped, not mixed with paraphyses. Spores 

 numerous, ovate. 



Chcetomium. Perithecium superfcial, 

 finally open at the mouth, clothed externally 

 with opaque hairs. Asci clavate, mixed with 

 paraphyses. Spores simple, ovate. 



Ascotricha. Perithecium thin, at length 

 bursthig, clothed with dark, subpellucid, 

 even, obscurely-jointed hairs. Spores sim- 

 ple, C(mtained in linear asci. Superficial, 

 at length free or resting on the investing 

 thallus, black. 



Orhicida, Cooke. Perithecium seated on 

 a distinct mycelium, reticulated. Ostiolum 

 obsolete ; sporidia subglobose ; paraphj-ses 

 simple or branched. 



PERISPO'RIUM, Fr.— A genus of Pe- 

 risporiacei (Ascomycetous Fungi), consisting 

 of minute, globular, free, punctiform sacs, 

 with fleshy or waxy walls, seated on an 

 obscure thallus, growing on leaves or stalks; 

 finally biu-sting and collapsing. The spores 

 are produced in large numbers in swollen 

 clavate asci (figs. 558, 559), which are un- 

 accompanied by paraphyses. 



Fio-. 558. 



Fig. 659. 



Pcrisporium disscminatum. 



Fig. .358. A perithecium in vertical section. Magni- 

 flcfi 100 diameters. 

 Fig. 559. An ascus detached. Magnified 300 diams. 



BiBL. Fries, Sum. Veq. 404 ; Syst. 3Iyc; 

 iii. 248 ; Berk. Ann. N. H. vi. 432. 



