122 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGOW. 



The number of leaves in a whorl ^•aries considerably. This 

 character is often difficult to determine owing to the compressed 

 condition in which most of the specimens are found, but occa- 

 sionally their number can be easily determined 



The following table illustrates this point. The first column 

 gives the number of leaves in a whorl as observed on specimens ; 

 the second column gives the numbers as shown on published 

 figures : — 



I. 11. 



Sphenophyllum verticillatum, Schl. sp. (= Sph. 

 Schlotheimii, Brongt. ), 

 emarginatum, Brongt., 

 cuneifolium, Sternb. sp. , ... 



var. saxifragEefolium, Sternb. sp. , 

 majus, Bronn sp., 



oblongifolium, Germar and Kaulfuss, 

 myriophyllum, Crepin, 

 tenerrimiim Ettingshausen, 

 trichomatosum, Stur, ... ... 9 ... — 



Thoni, Mahr, — ... 6 



This table shows a considerable variation in the whorl number, 

 a variation which is generally divisible by three. 



In addition to these wedge-shaped leaves, whorls of narrow 

 linear lanceolate leaves have been observed on some species of 

 Sphenophyllum. Stur was the first to figure these, and, misled 

 by their great similarity to the single-nerved narrow lanceolate 

 leaves of Calamocladus ( Asterophyllites), treated Sphenophyllutn 

 as the foliage of a Calamite} The fine specimen which Stur 

 here unites with his Calainites Sachsei " is probably the Spheno- 

 phyllum cuneifolium, Sternb. sp., and shows beautifully the 

 external aspect of the fructification. An equally good example 

 of Sphenophyllum, exhibiting the dimorphic condition of the 

 leaves, has been given by Seward.^ Simple lanceolate leaves 



' Stur, Carbon Flora d. Schatzlarer Schichten, Abth. II., Die Calamarien 

 dtr Carbon Flora d. Schatzlarer Schichten, PI. XI., fig. 2 (in Abhandl. 

 d. k. k. Geol. Reichsanstalt, Vol. XI., Abth. II., 1877). kSee also Verhandl. 

 d. L k. Geol. Reichsanstalt, No. 15, p. 329, 1878. 



- Stur, Carbon Flora, I.e., p. 180. 



" Mem. and Proc. Manchester Lit. and Phil. Soc, 4th Ser., Vol. III., 

 ^'■Sphenophyllum as a branch of Asterophyllites,'' fig. 1. 1890. 



