PERANEMA. 



[ 497 ] 



PERIDINIUM. 



branch with five setae, one from first, one 

 from second, and three from last joint ; pos- 

 terior branch with three setae from the last 

 joint only; intestine convoluted, with one 

 turn and a half; ova two. Aquatic. 



BIBL. Baird, Brit. Entom. p. 136. 



PERANEMA, Duj .A genus of Infusoria, 

 of the family Euglenia. 



Char. Form variable, sometimes nearly 

 globular, at others inflated posteriorly and 

 narrowed in front, where it becomes pro- 

 longed into a long flagelliform filament; 

 movement slow, uniform, forwards. 



P. globulosa (PL 24. fig. 59). Body almost 

 globular, more or less drawn out anteriorly, 

 with oblique wrinkles on the surface ; 

 aquatic; length 1-1400". 



BIBL. Dujardin, Infus. p. 353. 



PERICH^NA, Fr. A genus of Tricho- 

 gastres (Gasteromycetous Fungi), consisting 

 of little rounded membranous sacs of brown- 

 ish or yellowish colour, generally splitting 

 all round (transversely), and discharging 

 yellow spores and (few) free and elastic 

 filaments. The commonest, P. populina, 

 yellowish, and about as large as a mustard 

 seed, occurs on fallen poplar trees ; two 

 others occur in fir-plantations. 



BIBL. Berkeley, Hook. Brit. Fl. ii. pt. 2. 

 p. 321; Fries, Syst. Myc. p. 190, Summa 

 Veget. p. 459; Greville, Sc. Crypt. Fl. p. 252. 



PERICONIA, Tode. A genus of Stil- 

 bacei (Hyphomycetous Fungi), apparently 



nearly related to PACHNOCYBE, but with 

 the stem fistular, and the capitulum vesicular. 

 P. alaucocephala, Corda, has been found on 

 rotten linen. 



BIBL. Fries, Summa Veg. p. 168; Berk, 

 and Broome, Ann. Nat. Hist. 2 ser. v. p. 165. 



PERIDERM. See BARK. 



PERIDERMIUM, Lk. A genus of Cas- 

 omacei (Coniomycetous Fungi), distin- 

 guished from JEciDiuM by the sac-like 

 perithecium bursting irregularly, as if by a 

 circumscissile dehiscence. The type of this 

 genus is P. (jEcid.} Pini, found on the 

 leaves and bark of Scotch Firs. The spores 

 are covered with very numerous small 

 tubercles. See UREDINEI. 



BIBL. Berk. Brit. Flora, ii. pt. 2. p. 374; 

 Grev. Scot. Crypt. Fl. pi. 7 ; Tulasne, Ann. 

 des Sc. nat. 4 ser. ii. p. 176. pi. 10; De Bary, 

 Brandpihe, Berlin, 1853. p. 72. 



PERIDIN^A, Ehr. A family of Infu- 

 soria. 



Char. Body furnished with a membranous 

 carapace, from which a long flagelliform 

 filament issues, and which has one or more 

 furrows occupied by vibratile cilia, or exhi- 

 bits setae or minute spines upon the sur- 

 face. 



These Infusoria live either in the sea, or 

 in stagnant fresh water ; never being found 

 in infusions or decomposing water. 



Five genera : 



Carapace with rigid setae or points, but no transverse f Eye-spot present 1 . Chtetoglena. 



furrow nor longitudinal crest I Eye-spot absent 2. Chcetotyphla. 



Carapace smooth or rough, and with a transverse ciliated f Eye-spot present 3. Glenodinium. 



furrow, but no crest \ Eye-spot absent 4. Peridinium. 



Carapace with an incomplete longitudinal crest 5. Dinophysis. 



Dujardin appends the genera Chatoglena 

 and Cheetotyphla to his genus Trachelomonas 

 as uncertain, and arranges the genera Gle- 

 nodinium and Peridinium as stated under 

 the latter head. 



BIBL. Ehrenberg, Infus. p. 249; Dujardin, 

 Infus. p. 371. 



PERIDINIUM, Ehr. A genus of Infu- 

 soria, of the family Peridinaea. 



Char. Those of Glenodinium with the 

 absence of the red (eye-) spot. 



A flagelliform filament is present as well 

 as the cilia. Some species have horn-like 

 processes. 



Eleven species; two (fossil) doubtful. 

 Some of them are phosphorescent. 



P. cinctum (PL 24. fig. 9). Green ; not 

 phosphoresent; carapace subglobose, smooth, 



subtrilobed; no horns. Aquatic; length 

 1-580". 



P. fuscum (PL 24. fig. 11). Brown; not 

 luminous ; carapace ovate, slightly com- 

 pressed, smooth, acute in front, rounded 

 behind ; no horns. Aquatic ; length 1-430 

 to 1-290". 



P. tripos (PL 24. fig. 12). Yellowish ; 

 splendidly phosphorescent ; carapace urceo- 

 late, broadly concave, smooth, with three 

 horns, two very long, frontal and recurved, 

 the third posterior and straight. Marine ; 

 length 1-140". 



P. uberrimum, Allman. Cilia distributed 

 over the whole surface. Length 1-1000 to 



i-socr. 



Dujardin unites those species of the genera 

 Glenodinium and Peridinium which have no 



2K 



