OPHIDOMONAS. 



[ 556 ] 



OPHRYDIUM. 



For. 247 ; Parker and Jones, Ann. N. H. 

 3. viii. 229. 



OPHIDOM'ONAS, Ehr. Ageneric name 

 applied to slender, filiform, spiral (helical), 

 Vibrio-like bodies, of a brown or red colour, 

 with obtuse ends, and actively moving 

 through the water by means of an anterior 

 flagelliform filament. Ehrenberg places 

 them among the Infusoria, in the family 

 Cryptomonadina, and admits two species, 

 characterized bv the difference in colour. 

 One was found in fresh, the other in brack- 

 ish water. Length about 1-570", breadth 

 1-9000". In some the spire forms only half 

 a turn, in others two and a half turns. 



Probably an Alga. Is it the young state 

 of Spirulina ? 



BIBL. Ehr. In/us. 43, and Ber. Berl. Ak. 

 1840; Kent, Inf. 244. 



OPHI'OCLUS, Hincks. A genus of 

 Hydroid Zoophytes. 



Char. Stem branching, rooted by a creep- 

 ing stolon, capsules vnse-shaped; polypes 

 not retractile; body deeply constricted a 

 little below the base of the tentacles, which 

 surround a conical proboscis. Tentaculoid 

 organs borne on the stem and stolon, highly 

 extensile. Reproduction by fixed spore- 

 sacs. 



BIBL. Hincks, Brit. Hyd. Zooph. 230. 



OPHIOCY'TIUM, Nag. A genus of 

 Unicellular Algae. 



Char. Cells free, single, vermiculate, ob- 

 tuse at one end, mucronate at the other. 



O. majm (PI. 5. fig. 11), on freshwater 

 plants. 



BIBL. Rabenh. Alg. iii. 66. 



OPHIO'DES, Murr. A genus of Ixodea 

 (Acarina). Body thin, flat, circular ; on 

 foreign snakes. (Murray, EC. Ent. 203.) 



OPHIO'DES, Hincks. A genus of Hy- 

 droid Zoophytes. O mirabilis, on Laminaria 

 &c. (Hincks, Zooph. 230). 



OPHIOGLOSSA'CE^E. An Order of 

 Ferns, distinguished from all others by the 

 characters both of the vegetative and re- 

 productive structures. Fronds divided into 

 two parts, one foliaceous and sterile, the 

 other fertile, neither being rolled up in the 

 form of a crook. Sporanges destitute of 

 annulus, and split transversely nearly to the 

 base. 



Ophioglossum. Sporangia sessile, in two 

 rows, forming a narrow spike. 



Helminthostachys. Sporangia in crested 

 clusters, forming a long loose spike. 



Botrychium. Sporangia sessile, in two 

 rows on the spikes which form a panicle. 



OPHIOGLOS'SUM, Linn. The typic.il 

 genus of Ophioglossaceous Ferns, repre- 

 sented by the Adder's-tongue Fern, Ophio- 

 f/lossum vulgatum. Other tropical species. 

 (Hook. Si/n. 444.) 



OPHIONEL'LA, Kt. A genus of Peri- 

 trichous Infusoria. Solitary, elongate, 

 pesistome as in VorticeUa; contained in a 

 soft sheath. O. picta ; freshwater. (Kent, 

 Inf. 734.) 



OPHIOTHE'CA, Curr. A genus of 

 Myxogastrous Fungi, distinguished by a 

 simple peridium bursting longitudinally ; 

 capillitium twofold, viz. hyaline articu- 

 lated threads, to which the 'spores are at- 

 tached, and echinulate thicker branched 

 filaments. 



O. chrysosperma occurs on the inner bark 

 of dead trees. 



BIBL. Curr. Qu. Mic. Jn. ii. 240 ; Berk. 

 Outl. 310 ; Cook, Handb. 402. 



OPHRYDFNA, Ehr. A doubtful family 

 of Infusoria, corresponding to Vorticelliiia 

 with a carapace. 



Animals grouped in a gelatinous mass ... Ophrydium. 



/"Body attached to the bottom \ T ... 

 Animals J of the carapace by a stalk... f " 

 single, j Body not \ Carapace stalked ... Cothurnia. 



(. stalked. \ Carapace sessile . . . Vaginicola. 



BIBL. Ehr. Infus. 291 ; Clap, et Lach. 

 Etudes, 93. 



OPHRYD'IUM, Ehr. A genus of Peri- 

 trichous Infusoria, family Vorticellina. 



Char. Consists of a colourless, gelatinous, 

 rounded mass, either adherent or free, con- 

 taining numerous greenish Vorticdla-\\ke 

 animals imbedded and somewhat radiately 

 arranged within it ; freshwater. 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 31. 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 body 

 exhibits annular constrictions and longi- 

 tudinal folds, and contains scattered chloro- 

 phyll-granules, and a long, narrow, tortuous 

 nucleus. A distinct narrow elongated 

 O3sophagus is present. Ehrenberg remarks 

 that at first the individual bodies are united 

 in the centre by filaments, which subse- 

 quently disappear. The animals undergo 



