OPHRYDIUM. 



[ 473 ] 



ORTHOTRICHACE.E. 



OPHRYDIUM, Ehr. A genus of Infu- 

 soria, of the family Ophrydina. 



Char. Consists of a colourless, gelatinous, 

 rounded mass, either adherent or free, con- 

 taining numerous greenish Vorticella-like 

 animals imbedded and somewhat radiately 

 arranged within it. Aquatic. Length of 

 extended bodies 1-100 ; size of entire 

 mass from that of a pea to that of the fist, 

 and even more. 



O. versatile (PL 24. fig. 49, portion near 

 the surface; fig. 48, portion expanded by 

 pressure; fig. 50, separate animal). The 

 gelatinous mass or envelope has been de- 

 scribed as consisting of separate portions or 

 cells, and again as forming a homogeneous 

 whole. It somewhat resembles and has been 

 mistaken for frog's spawn. The bodies of 

 the animals, when extended, are spindle- 

 shaped, when contracted, oval, or nearly 

 spherical ; they have a row or ring of cilia 

 at the anterior margin of the peristome, also 

 a lid with a fringe of cilia, as in Opercularia, 

 &c. The body exhibits annular constrictions 

 and longitudinal folds, and contains scat- 

 tered chlorophyll-granules, and a long, nar- 

 row, tortuous nucleus. A distinct narrow 

 elongated oesophagus is present. Ehrenberg 

 remarks, that at first the individual bodies 

 are united in the centre by filaments, which 

 subsequently disappear. The animals un- 

 dergo the encysting process, and assume an 

 Acineta-form. When they leave the jelly, 

 a posterior ring of cilia is formed, as in Vor- 

 ticella, and the animals swim with the tail first. 



This organism bears some resemblance to 

 Coccochloris among the Palmellacese, yet it 

 appears decidedly animal. 



BIBL. Ehrenberg, In/us, p. 292 ; Stein, 

 In/us., passim. 



OPHRYOCERCINA, Ehr. A family of 

 Infusoria. 



It contains the single genus Trachelocerca, 

 E., which corresponds to Lachrymaria with 

 a tail. Dujardin unites these two genera, 

 so that the former becomes unnecessary. If 

 the family be retained, it should be called 

 TRACHELOCERCINA. 



OPHRYOGLENA, Ehr. A genus of In- 

 fusoria, of the family Colpodea. 



Char. Body ciliated all over ; a frontal 

 eye-spot present ; cilia arranged in longitu- 

 dinal rows. 



Three species. Stein remarks, that on 

 treating these animals with acetic acid, the 

 cilia became converted into a dense network 

 of curved and geniculate hairs, some as long 

 as the body. 



0. atra (PI. 24. fig. 53). Body ovate, com- 

 pressed, black, acute posteriorly; eye-spot 

 black, marginal; cilia whitish. Aquatic; 

 length 1-180". 



O. acuminata, brown; eye-spot red; 

 O.flavicans, yellowish; eye- spot red. Both 

 aquatic. 



Dujardin places this genus in his family 

 Bursarina. 



BIBL. Ehrenberg, In/us, p. 360; Stein, 

 In/us, p. 240; Dujardin, In/us, p. 506. 



ORBICULIN A, Lam. A genus of Fora- 

 minifera. 



0. numismatis (PI. 18. fig. 11-15). Found 

 in sea-sand. 



BIBL. That of FORAMINIFERA. 



ORIBATA, Latr. This genus has been 

 subdivided, and now constitutes the family 

 Oribatea. The position of three species is, 

 however, doubtful, viz. Acarus conferva, 

 Schr., living in fresh water, and creeping 

 upon Confervae, &c.; Oribata demersa,T)u]., 

 aquatic, with a cervical eye, and found upon 

 Hypnum inundatum ; and Oribata marina, a 

 marine species. 



We have found one species doubtfully re- 

 ferable to the above, agreeing with the cha- 

 racters of the Oribatea (p. 58) : body brown, 

 tarsi with a single claw, and no caruncle. 

 The individuals were creeping upon broken 

 stems of Ceratophyllum. 



BIBL. Gervais, Walckenaer's Apt. iii. 

 p. 251 ; Schrank, Ins. Austria, p. 511; Du- 

 jardin, L'Institut, 1842. p. 316; Koch, 

 Deutschl. Crustac. &c.; Duges, Ann. des Sc. 

 nat. 2 ser. ii. p. 46. 



ORTHODONTIUM, Schwagr. A genus 

 of Bryaceous Mosses, included under Bryum 

 by some authors. 



Orthodontium gracile, Schwagr. = Bryum 

 (Pohlia) gracile, Wils. 



BIBL. Wilson, Bryologia Britann. p. 218. 



ORTHOSIRA, Thw. See MELOSIRA. 



ORTHOTRICH ACE.E. A tribe of Pot- 

 tioid Mosses including several British genera. 



a. Papilla distinct, tuberculate, rarely obso- 

 lete-, peristome mostly pale, rarely orange- 

 coloured. 



1. ZYGODON. Calyptra dimidiate. Peri- 

 stome wanting, simple (external or internal) 

 or double ; external of thirty-two simple, Or- 

 thotrichoid,twin or bigeminate-conglutinate, 

 flat, pale, regular, rather fleshy teeth, formed 

 of a single row of cells, spreading or reflexed 

 on drying, and appressed to the capsule as 

 in Orthotrichum ; internal : eight to sixteen 

 linear, hyaline, more or less connivent, hori- 



