PEDICELLARI^. 



[ 494 J 



PELLIEiE. 



Interstices of the cells usually hyaline, but in 

 one species (P. selenatum) these are greenish. 



P. Boryanum (PL 10. fig. 48). Cells ar- 

 ranged in one or more circles around one or 

 two central ones; marginal cells gradually 

 tapering into two long subulate points ; 

 notch narrow. Diameter of outer cells 

 1-2/30 to 1-2220". 



P. granulatum (PI. 10. fig. 49). Cells six, 

 granular or punctate on the surface ; lobes 

 of marginal cells tapering. Diameter of 

 outer cells 1-1S50". 



The method of reproduction is noticed 

 under Desmidiace^, p. 1.96. 



BiBL. Ralfs, Brit. Desmid. p. 180; Cas- 

 pary, Bot. Zeit. viii. p. 786, 1850; Al. Braun, 

 Rejuvenescence, ^-c, Ray Soc. Vol. 1853, 

 passim, pis. 3 & 4. 



PEDICELLARIiE. See Echinoder- 



MATA, p. 219. 



PI. 37. fig. 3 represents a pedicellaria from 

 the common star-fish : the stalk is not 

 figured. 



The bird's-head processes of the polypes 

 (Polypi) are probably analogous organs. 



PEDICULUS, L.— A genus of Ano- 

 plurous Insects, of the family Pediculida?. 



Char. Legs all scansorial or prehensile; 

 thorax large, not constricted from the abdo- 

 men ; abdomen with seven segments ; an- 

 tennae five-jointed; mouth with a fleshy 

 rostrum. 



The species are human lice. 



Rostrum retractile, concealed beneath the 

 head, forming a soft tubular sheath dilated 

 at the end, where it is furnished with a 

 double row of hooks, and containing a horny 

 tube formed of four seta. 



P. capitis. Ashy-white, thorax elongate, 

 quadrate, abdomen ovate, laterally lobed, 

 segments blackish at the margin. Length 

 of male, 1-16"; of female, 1-8". 



P. vestimenti, body or clothes' louse (PI. 

 28. fig. 3). Dirty white, elongato -ovate ; 

 head much produced ; thorax contracted in 

 front; abdomenwith the segments indistinctly 

 indicated. Length about 1-8". 



P. tabescentium, distemper-louse. Pale 

 yellow^ ; head rounded ; antennae long ; 

 thorax large and quadrate ; abdomen large, 

 the segments intimately united. 



Doubtfully British. 



BiBL. Denny, Anoplur. Monogr. 



PELARGONIUM. See Pollen, Ra- 

 PHiDES, and Hairs. 



PELECIDA, Duj.— A genus of Infusoria, 

 of the family of Trichodina. 



Char. Body flexible, contractile, oblong, 



compressed, rounded behind, recurved like a 

 hatchet in front, ciliated all over, and fur- 

 nished with a mouth, which is either visible, 

 or shown to exist by the presence in the in- 

 terior of various objects swallowed by the 

 animals. 



P. rostrum (PI. 24. fig, 39) = Loxodes 

 rostrum, E., diifers from the Paramecina, D,, 

 by the absence of a contractile integument. 



BiBL. Dujardin, Infus. p. 403. 



PELLIA. — A genus of Pellieae (frondose 

 Hepaticaceae). P. epiphylla (fig. 561) is not 

 uncommon in damp shady places, by springs 

 and wells, w^here it grows rapidly. Its pedi- 

 cels are silvery-white, and the capsules pale 

 brown, and when the valves are fully ex- 

 panded, the elaters form an elegant tuft in 

 the middle. The form of the frond varies 

 somewhat according to the degree of moist- 

 ure of the habitat. 



BiBL= Hooker, Brit. Jung. pi. 47, Brit. 

 Flora, ii. pt. 1. p. 130; Endlicher, Gen. 

 Plant. Supp. i. No. 472-5; Ekart, Syn. 

 Jung. p. 63. pi. 7 & 13. 



Fig. 561. 



Pellia epiphylla. 

 Magnified 2 diameters. 



PELLIEiE.— A tribe of Liverworts or 

 Hepaticae, nearly allied to the Jungerraan- 

 nieae in the character of the fructification, 

 but having a lobed thalloid frond, traversed 

 by a mid-nerve, from which the fruit-stalks 

 arise. 



British Genera. 



1. Blytia. Fructification emerging from 

 the end of the rib below the apex of the 

 frond, at length dorsal. Perichaete 4-5- 



