TTERYGIUM. 



[ 645 ] 



PUOCINIA. 



upon bats. Several species have been de- 

 scribed. 



BiBL. Gervais, WalcJcenaer^s Aptbres, iii. 

 227 ; Dufour, Ann. Sc. N. xvi. 98, xxv. 9 ; 

 Koch, Deutschl. Crustac. ; Murrav, Ec. Ent, 

 175. 



PTERYGIUM, Nyl. -A genus of Colle- 

 niaceous Liclieus. 2 species, ou calcareous 

 rocks. (Leio-liton, Lichen Fl. 12.) 



PTERYGO'NIUxAI, Sw. — A genus of 

 Alosses. See Neckeea. 



PTILIDIUM, Nees.— A genus of Jun- 

 germanuiete (Ilepaticte), containing one ele- 

 gant British species, P. ciliare, frequent on 

 heaths and rocks in subalpine districts, but 

 rarelv found in fruit. 



BiBL. Hooker, Br. Fl. ii. 126; Br. Jung. 

 pi. Co ; Ekart, Juny. pi. 5. fig. 36. 



PTILO'TA, Ag. — A genus of Ceramiacefe 

 (Florideons Algfe), with flat feathery fronds 

 a few inches high ; of a deep red colour, 

 growing on Laminarm or Fuci, or on rocks 

 between tide-marks. The fructification 

 consists of: — 1. clustered roimdish favell<e 

 containing spores, terminating the ultimate 

 pinnules, and surrounded by an involucre 

 of subulate ramuli, or naked ; 2. tetrahedral 

 tetraspores on short pedicels fringing the 

 pinnules. Antheridia have not been ob- 

 served. F. plumosa (PI. 4. fig. 16). 



BiBL. Harvey, Mar. Alg. 159, pi. 22 A ; 

 Flnjc. Br. pi. 70 ; Greville, Aly. Br. pi. 16 ; 

 Niigeli, Algensi/stem, pi. 6. figs. 38-42. 



PTYCHOG'RAPHA, Nyl.— A genus of 

 Graphidei (Lichenaceous Lichens). 1 sp., 

 on decorticated mountain-ash. (Leighton, 

 Lich. Fl. 392.) 



PTYCIIOS'TOMUM, St.— A genus of 

 Holotrichous Infusoria. Free, ovate, un- 

 svmmetrical, mouth ventral. 2 species, in 

 the intestines of Aunulata (Tubifex), and 

 MoUusca {Pahulina). (Kent, Inf. 541.) 



PTYGU'RA, Ehr.— A genus of Rotatoria, 

 of the family Ichthydina. 



Char. Eyes none; no hairs upon the 

 body ; tail-like foot cylindrical, simply trun- 

 cate. 



Teeth three in each jaw ; anus* situated 

 at the end of the tail-like foot. 



P. melicerta (PL 44. fig. 21). Body terete- 

 clavate, turgid in front, hyaline ; mouth 

 with two little hook-like horns ; cervical 

 process single and smooth. Freshwater ; 

 length 1-144". Ehrenberg questions whe- 

 ther this is not a young form of another 

 geniis. 



BiBL. Ehrenberg, Inf. 387 ; Hudson, 

 Mn. M. Jn. xiv. 165. 



PTYXID'IUM, Perty.— A genus of Eu- 

 chelia. It shoidd probably be included in 

 Leucophrys. 



BiRL. Pritchard, Infusoria, p. 615. 



PUCCIN'IA, Persobn.— A genus ofUre- 

 dinoi (Ilypodermous Fungi), containing 

 numerous parasitical species, growing upon 

 the leaves and other herbaceous parts of the 

 higher plants, forming "mildews," and Avith 

 their Uredinous forms, "rusts" &c. Tliese 

 Fungi have received considerable attention 

 lately from Tulasno, l)e Bary, and others ; 

 and it appears that the genera Uredo and 

 others have no distinct existence, but are 

 preparatory forms of Puccinia and other 

 genera noticed under Uredinei. In the 

 article iEciDiUM w^e have described the 

 twofold reproductive structures, namely the 

 spermogonia and the perithecia (figs. 6 & 6 a, 

 p. 19 ; PL 26. figs. 1-4), producing respect- 

 ively the spermatia (supposed to have the 

 office of spermatozoids) and the spores. In 

 Puccinia three forms of reproductive organs 

 occur : first, spermogonia analogous to those 

 of ALcidium ; then the forms called Uredines 

 (chiefly of the supposed genus Trichohasis), 

 producing globular unilocular bodies, shortly 

 stalked, and with transparent walls, but 

 with yellov/ or orange-coloured contents ; 

 and lastly the true Puccinice, containing 

 bilocuLar spores borne on short stalks, and 

 having a dark-brown integument. The 

 latter present remarkable phenomena in 

 germination, which may be best observed 

 in those which sprout without becoming 

 detached from the matrix, such as P. gra- 

 minis, which however rem.aiu quiescent 

 until the spring foUoAving their development, 

 whUe P. Glecho)n(e,Buxi, Dia}dhi, sinAotliers 

 germinate in the same summer. The bilo- 

 cidar spores have each one pore (analogous 

 to the pores of PoLLEN-grains), from which 

 extends a filamentous process, ultimately 

 giving rise to four short processes, each 

 terminating in a pointed process bearing a 

 sporidium, of more or less curved elliptical 

 form. About the time when these fall off", 

 the filament bearing the four processes be- 

 comes divided by septa into four chambers, 

 but then appeal's to die. The sporidia ger- 

 minate and produce a filament, which, in- 

 stead of becoming the basis of a mv'celium, 

 reproduces a sporidium smaller than the first. 

 More is said respecting these remarkable 

 organisms under the head of Uredinei. 



The Puccinice present the following ge- 

 neral characters : — The spermogonia rare, 

 scattered on either face of the infested leaf. 



