GOSSYPIUM. 



[ 296 ] 



GRAMMONEMA. 



The polypidom, as well as the crust, con- 

 tain spicula of various forms imbedded in 

 them, a specimen of which is exhibited in 

 PI. 33. fig. 27. 



BIBL. Johnston, Brit. Zoophyt. p. 166. 

 GOSSYPIUM. See COTTON. 

 GOUT-STONES. See CHALK-STONES. 

 GRACILARIA, Grev. A genus of Rho- 

 dymeniaceae (Florideous Algae), with feathery 

 fleshy-cartilaginous fronds, 6 to 12" or more 

 long, of a red or purplish colour, the central 

 substance of which is composed of large 

 cells, the cortical of closely-packed hori- 

 zontal filaments. The spores are formed 

 in tubercles consisting of a thick coat com- 

 posed of radiating filaments, containing a 

 mass of minute spores on a central placenta. 

 The tetraspores are imbedded in the cells of 

 the surface. G. confervoides is the only 

 common species; it grows from 3 to 20" 

 long, and as thick as small twine. 



BIBL. Harvey, Brit. Mar. Alg. p. 128. 

 pi. 16 C, Engl. Bot. pi. 1668. 



GRAMMATONEMA, Ag. A genus of 

 microscopic plants, sometimes placed among 

 the Diatomaceae, either as distinct or included 

 under Fragilaria. But the membrane is 

 scarcely siliceous, and does not withstand 

 heat or acids. Kiitzing places it among the 

 Desmidiaceae. 



Char. Cells quadrangular, very narrow, 

 closely conjoined into an elongated fila- 

 ment. 



G. striatulum, K. ( Grammonema Jurgensii, 

 Ralfs) is slender, yellowish -brown; the cells 

 three to eight times longer than broad, 

 slightly attenuated to each end, and sepa- 

 rated at the angles. It does not change 

 colour in drying ; its variety, /3. diatomoides, 

 turns green in drying. Marine. 



BIBL. Kiitzing, Sp. Alg. p. 187 ; Ralfs, 

 Ann. Nat. Hist. xiii. p. 457. pi. 14. fig. 5. 



GRAMMATOPHORA, Ehr. A genus of 

 Diatomaceae. 



Char. Frustules in front view rectangular, 

 at first adnate, but afterwards forming zig- 

 zag chains ; vittae two, longitudinal, inter- 

 rupted in the middle and more or less curved. 

 Marine. Valves furnished with transverse 

 striae, in most invisible by ordinary illumi- 

 nation, and in a few so difficult of detection 

 that the valves have been regarded as TEST 

 OBJECTS. 



Kiitzing describes thirteen species. 



G. marina (PL 1. fig. 14; PI. 12. fig. 35 ; 



PL 14. fig. 37). Striae invisible by ordinary 



illumination; vittae near the middle semi- 



circularly curved outwards; valves linear, 



gradually attenuated towards the obtuse 

 ends; length 1-108 to 1-420". 



The form and structure of the frustules 

 and valves appears greatly to vary. Some- 

 times the frustules are nearly square, at 

 others six times as long as broad. In some 

 specimens the valves are suddenly, at others 

 uniformly inflated at the middle (PL 1. fig. 

 14 b; PL 12. fig. 35 c), some have the ends 

 capitate. Again, in some valves there is a 

 median line and a small central nodule 

 (PL 12. fig. 35 c), in others there is neither 

 median line nor nodule, but a large internal 

 ring (PL l.fig. 14 b). Lastly, in some valves 

 the striae extend over the whole of the valves, 

 while in others they are deficient at their ends. 

 Some of these variations have formed the 

 basis of distinct species, but probably with 

 little reason. 



A variety, G. subtilissima, Bail. (PL 14. 

 fig. 38 a, b), has been pointed out by Prof. 

 Bailey, in which the form of the frustules 

 and valves agrees with the above characters, 

 but in which the transverse striae are ex- 

 tremely difficult of detection when mounted 

 in balsam. 



G, serpentina. Striae distinct; vittae large, 

 serpentine, with the end curved inwards to 

 form a kind of hook ; length 1-200". 



BIBL. Ehrenberg, Ber. d. Berl. Akad. 

 1839. p. 126, and Ber. ejusd. 1840, &c.; 

 Kiitzing, Sp. Alg. p. 120; Ralfs, Ann. Nat. 

 Hist. 1843. xi. p. 449; Bailey, Silliman's 

 Journal, vii. 



GRAMMITIDE^E. A sub-tribe of Poly- 

 podaeous Ferns, with naked sori, containing 

 three genera : 



I. GRAMMITIS. Sori linear or roundish, 

 seated on certain arms of the veins. Veins 

 simple or forked, scarcely anastomosing. 



II. SELLIGN^SA. Sori linear or roundish, 

 seated on certain arms of the veins. Veins 

 very much branched, anastomosing in 

 more or less regular meshes, without free 

 veins. 



III. SYNAMMIA. Sori oblong, seated 

 on the back of the lowest venule. Veins 

 branched, anastomosing into more or less 

 regular meshes, with free venules. 



GRAMMITIS, Swartz. A genus of 

 Grammitideae (Polypodaeous Ferns), synony- 

 mous with Ceterach. Grammitis ceterach, or 

 Ceterach ojficinarum,is an indigenous species; 

 the back of the fronds is densely clothed 

 with chaffy scales and hairs, composed of 

 cellular tissue. 



GRAMMONEMA, Ag. = GRAMMATO- 



