ORTHOTRICHUM. 



[ 474 ] 



OSCILLATORIA. 



zontal cilia, or resembling the outer teeth. 

 Capsule pyriform, grooved, more rarely gla- 

 brous, without an annulus. 



II. ORTHOTRICHUM, Hedw. Calyptra 

 campanulate, plaited. Peristome absent, 

 simple or double. External of thirty-two 

 geminate (sixteen) (fig. 487- p. 435), or bi- 

 geminate (eight) (fig. 542) teeth, more rarely 

 of sixteen entire, undivided teeth, granular, 

 fleshy, or brittle, mostly pale, rarely orange- 

 coloured, erect, afterwards reflexed, arising 

 below the mouth of the capsule. Internal : 

 eight or sixteen cilia, simple, hyaline, or 

 (rarely) resembling the teeth. Vaginule 

 ochraceous. Inflorescence monoecious or 

 dioecious. Capsule without an annulus, 

 more or less pyriform, grooved, rarely gla- 

 brous; operculum capitate, conical. 



b. Papilla mostly obsolete, rarely distinct,, 

 peristome always coloured, purple, red or 

 orange. 



III. GLYPHOMITRIUM. Calyptra cam- 

 panulate, large, totally enclosing the capsule, 

 deeply laciniate, plaited. Peristome com- 

 posed of sixteen short, lanceolate, densely 

 trabeculate, entire teeth, with a central line, 

 approximated in pairs, incurved, arising be- 

 low the orifice, orange-coloured, smooth 

 (fig. 287, p. 293). Inflorescence monoecious. 



IV. BRACHYSTELIUM. Calyptra as in 

 the preceding, altogether or almost entirely 

 covering the capsule, mitre-shaped, with long 

 and repeated laciniations, slightly plaited. 

 Peristome like that of Trichostomum, the 

 teeth being split more or less down to the 

 base, into two arms. Inflorescence monoe- 

 cious. 



V. GUEMBELTA. Calyptra dimidiate, other- 

 wise like the following (figs. 293-295, p. 

 299). 



VI. GRIMMIA. Calyptra mitre-shaped, 

 laciniate, scarcely exceeding the operculum, 

 and smooth, or else shorter. Peristome 

 simple, teeth sixteen, lanceolate, with a me- 

 dian line, trabeculate, often however fissile, 

 hence very polymorphous, more or less split, 

 as far as the middle, into two or four teeth, 

 or into two arms down to the base (fig. 292, 

 p. 299). 



ORTHOTRICHUM, Hedwig. A genus 

 of Orthotrichaceae (Pottioid Mosses), grow- 

 ing in round tufts, fertile at the summit, on 

 trees and stones, never on the earth. There 

 are numerous British species, which are re- 

 markable for the apophyses (sometimes 

 having stomata) and for the varied character 

 of the outer peristome, the thirty-two teeth 



of which are variously conjoined, so as to 

 appear as thirty-two, sixteen, or eight. The 

 calyptra is mostly covered with hair-like 

 processes (fig. 476, p. 433). 



Fig. 541. 



Fig. 542. 



Fig. 541. Orthotrichum pulchellum. Magn. ISdiams. 

 Fig. 542. Orthotrichum pollens. Fragment of peri- 

 stome. Magn. 50 diams. 



BIBL. Wilson, EryologiaErit. p. 185; 

 Hooker, Brit. Fl. ii. pt. 1. p. 57. 



OSCILLATORIA, Vauch. A genus of 

 Oscillatoriaceae (Confervoid Algae), distin- 

 guished from the allied forms by the simple, 

 rigid, elastic filaments, forming a stratum in 

 a common gelatinous matrix. The filaments 

 are enclosed singly in tubular cellulose 

 sheaths, open at the ends, from which the 

 fragments emerge when they are broken 

 across (PL 4. fig. 8). The young filaments 

 or growing extremities are continuous and 

 scarcely striated, but by degrees transverse 

 striae appear, sometimes very close together, 

 sometimes distant, which striae indicate a 

 constriction and final fission in the substance 

 of the filament, which, when old, readily 

 breaks at these places. The internal struc- 

 ture of the filament is obscure ; it would 

 seem to be composed wholly of protoplasmic 

 substance, the joints not possessing special 

 cellulose coats, but the substance of the 

 filament, although apparently solid, seems 

 sometimes less dense internally, since we 

 have noticed a kind of hour-glass contraction 

 intermediate between the striae after the ac- 

 tion of thick syrup (by endosmose) and after 

 desiccation. The curious rounding-off of 

 the separated ends of dividing filaments (PI. 

 4. fig. 8, right-hand figures) seems to depend 

 on some power of expansion of an outer 

 thicker layer of the substance of the fila- 

 ment. The motion of the filaments has 



