THE CLUB-MOSSES 183 



organs, such as those which we have already met 

 with in the herbaceous Miadesmia. This is a 

 more advanced method than anything we find 

 among living Club-mosses. We will begin with 

 the simpler, heterosporous cones, which seem to 

 have been in the majority, though the seed-like 

 type was also quite common. 



The typical cones of Lepidodendron had a 

 characteristic structure. The axis of the cone 

 bore a great number of spirally arranged or 

 sometimes whorled sporophylls, closely packed 

 together. Each fertile leaf or sporophyll con- 

 sisted of a more or less horizontal basal part, ter- 

 minating in a broader blade, which turned ver- 

 tically upwards and usually had a shorter down- 

 ward prolongation as well. The sporangium was 

 attached along its whole length to the upper sur- 

 face of the horizontal portion of the leaf. Its 

 length was sometimes very considerable in one 

 specially fine cone the sporangium is almost two 

 centimetres long by five millimetres wide; these 

 are, perhaps, the largest Cryptogamic sporangia 

 known. The ligule was placed at the far end 

 of the sporangium, just below the blade of the 

 sporophyll, showing that the whole of the hori- 

 zontal part represents a long-drawn-out leaf-base. 

 The insertion of the sporangium along its whole 

 length on the elongated base of the fertile leaf 

 is characteristic of the cones of Lepidodendron; 



