XXXV] GKETOPSIS 317 



Gnetopsis. Eenault. 



This generic name was given by Renault^ to some small 

 petrified seeds from the Stephanian of Grand' Croix and to 

 impressions from the Commentry coal-field which he beheved 

 to belong to some Gnetaceous plant. Saporta and Marion* and 

 other authors have accepted these seeds as evidence of the 

 existence of Palaeozoic Gnetales: it has, however, been shown^ 

 that Gnetopsis has no claim to such relationship and is a type of 

 seed closely alHed to Conostoma. Renault described three species, 

 afterwards adding three from another locahty*; the genus is 

 recorded also from Commentry^ and Gard*- More recently 

 Depape and Carpentier' have described examples from the West- 

 phaUan of Valenciennes which they place in the Pteridosperms 

 in accordance with the conclusion of Ohver and Sahsbury. 

 Gnetopsis has also been discovered by Mr Hemingway in the 

 Middle Coal Measures of England^ (fig. 494, H). 



Gnetopsis elliptica Renault. 



The seeds of this species, slightly oval in section, occur in 

 groups of 2 — 4 in a cupular investment (fig. 506, E, p. 359) 

 described by Renault as an ovary but correlated by Oliver and 

 Sahsbury with the cupule which surrounds the single ovule of 

 Lagenostoma. The cupule is lined with hairs similar to those 

 on the wall of the cupule of Lagenostoma. A characteristic 

 feature of the French seeds is the presence of three or four 

 long plumes of hairs at the apex (fig. 494, E, F). As seen in 

 fig. 494, E, a small lagenostome (pollen-chamber) rests on the 

 roof of a broad phnth precisely as in Conostoma, and four vascular 

 bundles, corresponding to the six bundles in Conostoma, pass 

 into the apical cap of sclerous tissue enclosed by a sarcotesta, 

 sa (fig. 494, E, G). A 'tent-pole' prolongation (fig. 494, E, t) 

 occurs at the apex of the prothallus. Renault described a portion 

 of the integument as consisting of lacunar tissue which Oliver 

 and Sahsbury homologise with the superficial mucilaginous layer 



1 Renault (84) Pis. xix.— xxn. ^ Saporta and Marion (85) p. 181. 



3 Oliver and Salisbury (11). * Renault (96) A. p. 85, PI. XLn. 



6 Renault and ZeiUer (88) A. p. 640, Pis. 72, 82. 



« Grand'Eury (90) A. PI. vi. fig. 6. 



' Depape and Carpentier (13) PI. xn. figs. 1—3. " Kidaton (90) p. 64. 



