44 TRANSACTIONS, NATURAL HISTORY SOCIETY OP GLASGOW. 



Memarks.— The leaf-cushion consists of a clearly-defined and 

 more or less elevated rhomboidal or fusiform area, generally 

 longer than broad, whose lateral angles are usually prominent. 

 On the greater number of specimens the leaf-cushions are flat or 

 very little elevated (fig. 3 ). This condition is most probably due to 

 pressure. From the deep impressions of Lepldodendra frequently 

 found, the leaf-cushions, when uncompressed, must have possessed 

 a considerable amount of elevation in many, if not in all species. ^ 



Fig. 3. — Lepidodendron acidea- 

 tum, Sternb., Lower Coal 

 Measures, Stevenston (No. 



2482). 



Fig. 4. — Leaf cushion 

 of Lepidodendron 

 acideatum, Sternb., 

 slightly enlarged. 

 For description see 

 text. 



Within the cushion, usually, situated slightly above the centre 

 is the rhomboidal or transversely elongate rhomboidal leaf-scar 

 (a) fig. 4, whose upper and lower angles arc more or less rounded, 

 the two lateral acute and generally produced as two downward 

 keels (6). Within the leaf -scar (a) and usually below the centre are 

 three punctiform cicatricules, the central of which is the scar of 

 the foliar bundle. The two lateral cicatricules are possibly 

 glandular organs and have been termed the parichnos (f). 



1 The following specimens in my collection show this very well: — Ltpi- 

 dodtndron Vdtheimianum, Sternb. (No. 2453) ; Lep. Vtltheimianum, 

 Stbg., (?) (No. 61) ; and Lepidodendron ophiurus, Bgt., (?) (No. 1474). 



