GRAMMATOPIIORA. 



363 ] 



GRANTIA. 



microscopic marine plants, by some referred 

 to the Diatoinaceae, by others, including 

 Ralfs and Kiitzing, to the Desmidiaceae. 



The recent observations of Smith show 

 that it belongs to the former family, and to 

 the genus Fragilaria. 



G. striatulum=Fr. striatula. 



GRAMMATOPH'ORA, Ehr. A genus 

 of Diatoniaceae. 



Char. Frustules in front view rectangular, 

 at first adnate, but afterwards forming zig- 

 zag chains ; vittso two, longitudinal, inter- 

 rupted in the middle and more or less curved. 

 Marine. 



Valves linear or elliptical ; furnished with 

 transverse striae, in most, invisible by ordi- 

 nary illumination, and in a few so difficult of 

 detection that the valves have been regarded 

 as TEST OBJECTS. Sometimes a median 

 and terminal nodules are present. 



Rabenhorst describes eleven species. Four 

 are British ; one doubtful : 



G. marina (PI. 1. fig. 14; PI. 16. fig. 35). 

 The markings or striae are invisible by ordi- 

 nary illumination 5 vittae near the middle 

 semicircularly curved outwards ; valves 

 linear or elliptical, gradually attenuated 

 towards the obtuse ends ; striae transverse ; 

 length 1-108 to 1-240". 



The form and structure of the frustules 

 and valves appear greatly to vary. Some- 

 times the frustules are perfectly 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. 146; PI. 16. fig. 35 c), some have the 

 ends capitate. Again, in some valves there 

 is a median line and a small central nodule 

 (PI. 16. fig. 35 c) ; in others there is neither 

 median line nor nodule, but a large internal 

 ring (PI. 1. fig. 14 6). 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. siibtilissima, Bail. (PI. 1. 

 fig. 15 a, 6), 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. macilenta. Fr. slender, often curved ; 

 vittae as in the last ; valves linear, slightly 

 inflated at middle and ends. Marine; 

 length 1-300". 



G. serpentina. Vittae long, serpentine, with 



the end curved inwards to form a kind of 

 hook; striae oblique. Marine; length 1-200". 



G. ? Balfouriana. Vittae straight; valves 

 linear, inflated in the middle, and with 

 rounded ends. Freshwater. 



BIBL. Ehrenberg, BerL Abh. 1839. 126, 

 and Ber. 1840, &c. ; Kiitzing, Sp. Aly. 120; 

 Bailey, Silliman's Journ. vii.; Smith, Br. 

 Diat. ii. 42 ; Schiff, Schultze's Archiv, iii. 

 81 ; Rabenhorst, FL Alg. i. 303 ; Petit, Jn. 

 Mic. Soc. 1881, i. 109. 



GRAMMITID'EJE. A family of Poly- 

 podiaceous Ferns. 



Char. Son on the back of the fronds, 

 more than twice as long as broad, usually 

 linear. Genera : 



Jamesonia. Sori oblong, on the flabellate 

 veins of the back of the pinnae, not reaching 

 the margin. 



Brainea. Sori continuous along trans- 

 verse veins near the midrib, also produced 

 along the veins towards the edge of the 

 frond. 



Notochl&na. Sori marginal, oblong or 

 rounded, then confluent into a marginal line, 

 the edge of the frond frequently inflexed to 

 form an involucre ; veins free. 



Monogramma. Sori linear, close to the 

 midrib on one or both sides. 



Gymnogramma. Sori on the veins of tho 

 under surface of the frond, linear, simple or 

 forked. 



Meniscium. Sori oblong or linear, occu- 

 pying the connivent transverse veinlets of 

 the simple or once pinnate fronds. 



Antrophyum. Sori on the veins, imper- 

 fectly reticulated. 



Vittaria. Sori in continuous marginal or 

 slightly intramarginal lines. 



Tcenitis. Sori linear, the line sometimes 

 interrupted, central or submarginal. 



Drymoglossum. Like Tanitis, bat the 

 fronds dimorphous. 



Hemionitis. Sori continuous along the 

 veins, and copiously reticulated, sometimes 

 also slightly developed between them. 



GRAMMI'TIS, Swartz., is merged into 

 Polypodium and Gymnogramma. Ceterach 

 is sometimes taken for a Grammitis. 



GRAMMONE'MA, Ag. = GRAMMATO- 



NEMA. 



GRAN'TIA, Fleming. A genus of 

 Sponges. 



Char. Form variable; firmish and in- 

 elastic, usually white, with a close but po- 

 rous texture, and composed of a gelatinous 

 base, with imbedded calcareous spicula; ori- 

 fices distinct. Marine. 



