MESOGLOIA, 



[ 501 ] 



METOPIDIA. 



2 species; fi-esliwater and marine. (Ivent, 

 Inf. (535.) 



"MESOGLO'IA, Ag.— A genus of Clior- 

 dariaceas (Fucoid Algae), with filiform, 

 much-branched, gelatinous fronds ; the axis 

 of the filaments composed of interlacing 

 longitudinal cells, with gelatinous interposed 

 matter ; the periphery of radiating, dicho- 

 tomous, coloured filaments. The fructifi- 

 cation consists of unilocular and multilocular 

 sporanges; the former are ovate sacs (fig. 

 ^8) occurring attached to the ramuli of 



Fig. 458. 



Mesogloia vermicularis. 

 Peripheral ramiili, unilocular sporanges and the fila- 

 ments upon which the jointed sporanges arise. 



Magnified 50 diameters. 



the periphery ; the latter are produced by 

 ramifications of other ramuli siu-rounding 

 them (fig. 458). Both kinds produce cili- 

 ated zoospores, which germinate. M. ver- 

 micularis (figs. 458, 459), an olive-gi-een 



Mesogloia vermicularis. 



Portion of a filament. 

 Magnified 10 diameters. 



or yellowish frond, 6" high, is common on 

 rocKs and stones between tide-marks. M. vi- 

 rescens, a smaller species, is not uncommon. 



BiBL. Harvey, Mar. Alg. 47, pi. 10 B ; 

 Phyc. Brit. pis. .31 & 83 ; Thuret, Ann. Sc. 

 Nat. 3 ser. xiv. 237, pi. 27. 



MESOT^'RIUM, Nag.— Probably iden- 

 tical with Palmoglcca, (Archer, Qu. Mic, 

 Jn. iv. n. s. 109.) 



METACYTRIS, B. & R— One of the 

 Ci/therid(e : carapace tumid and cordate ; 

 upper antennae long and setose. Lakes and 

 rivers of England, Ireland, and Holland. 



BrBL. Bradv and Robertson, Ann. N. H. 

 4, vi. 19 ; ix. 51. 



METACYS'TIS, Cohn.— A genus of 

 Holotrichous Infusoria. 



Char. Free, ovate or elongate, ringed, 

 vesicular behind. 



M. tnmcata, among decaying marine 

 algse. (Kent, Inf. 511.) 



METAMORPHOSES of Tissues.— The 

 degenerations of the tissues, characterized 

 by an alteration in their quality and impair- 

 ment of function. They are divided into 

 metamorphoses and infiltrations. The meta- 

 morphoses are characterized by the direct 

 change of the albuminoid constituents of a 

 tissue into a new material, which is usually 

 followed by the destruction of the histo- 

 logical elements, and the softening of the 

 intercellular substance. They include fatty, 

 mucoid, and colloid degeneration. 



BiBL. Green, Path, and Morh. Anat. 



METEORITES.— In transparent sections 

 of small fragments of meteorites, many 

 mineral substances may be recognized here 

 and there ; but the microscope and even 

 polarized light fail to distinguish the kinds 

 of crystals. It is best to examine the 

 bruised debris ; and minute crystals may 

 be sorted out, and removed for microscopic 

 examination. 



BiBL. Maskelyne, Proc. Roxj. Soc. 1870. 



METOPI'DES, Quenn.— Like Metopus, 

 but with two or more posterior setfe. M, 

 contorta, freshwater. (Kent, Inf. -582.) 



METOPIDIA, Ehr.— A genus of Rota- 

 toria, of the family Euchlanidota. 



Char. Eyes two, red, frontal ; foot forked j 

 carapace depressed or prismatic; anterior 

 and upper part of head naked or uncinate ; 

 no hood. = Lepadella with two frontal 

 eyes. Lorica closed beneath. 



M. triptera (PI. 44. fig. 7). Carapace 

 ovate, accurately trilateral, crested on the 

 back. Freshwater ; length 1-288 to 1-144". 



Four other species. 



