244 GLOSSOPTERIS AND ITS ALLIES, 



them distinct, although with evident reluctance, chiefly on account 

 of the simple non-pinnate leaf in Glossopteris. 



The margins of the leaflets are not always entire in Sagenopteris, 

 Nathorst having described a species, aS'. dentata* in which they 

 are largely dentate. Notwithstanding that this is uncommon in 

 Sagenojyteris, so far as our experience has gone, nothing of the 

 sort occurs in Glossopteris, and probably between us we have 

 examined many thousand specimens. 



That the mid-rib in Glossopteris does evanesce before reaching 

 the apex of some leaves is equally true, such for instance is the 

 case in G. longicaulis, Feist., f but in general it is at about the 

 last fourth towards the apex and often less that the mid-rid com- 

 mences to dissolve into the secondary veins. On the other hand, 

 in all the short and broad-leaved forms of Sagenojiteris the mid-rib 

 disappears low down, and even in a limited number of cases it is 

 difiicult to detect more than the rudiment of a mid-rib. The latter 

 is the case in Nathorst's S. undtdata,l Fontaine's S. rhoi/olia,^ 

 and Schenk's *S'. Mantelli,\\ from the Wealden Coal-measures of 

 Osnabriick. But in some long-leaved species of Sagenopteris, e.g., 

 S. Phillijjsii, Phill., from the Yorkshire Oolite, figui'ed by Lindley 

 and Hutton,11 the mid-ribs resemble those in Glossopteris leaves, 

 and are strong and persistent almost to the apices. Also in 

 «S'. polyphylla, Feist.,** there is a strong mid-rib, whilst in another 

 plant referred provisionally to Sagenopteris by Feistraantel under 

 the name of S. (?) longi/olia,jf this vein extends almost to the 

 apex. In fact Glossopteris longicaulis, Feist., and Sagenopteris (?) 

 longifolia, Feist., may be regarded as transitional forms between 



* Floran vid Bjuf, 1878, i. t. 2, f. 5-7. 



tPal. Indica (Gondwana Flora), 1881, hi. Pt. 1, Suppl. p. 53, t. 31, f. 1, 3, 



X hoc. cit. t. 2, f. 4. 



§ Mon. U.S. Geol. Survey (Powell's), 1883, vi. t. 49, f. 5. 



II Beitrage zur Flora der Vorwelt, Pt. 4, p. 20, t. 10, f . 5. 



TI Foss. Flora, i. p. 63, t. 63. 



** Pal. Indica (Gondwana Flora), 1881, iii. Pt. 3, p. 113, t. 41a, f. 3 and 4. 



+t Loc. cit. t. 40«, f. 1. 



