LEPIDOSTROBUS 175 



stalked cones were borne either on Halonial branches 

 or on the twigs of the young growth. 



The general characters of the cones of Lepidostrobus 

 are those of Lycopodiaceous fructifications. In habit 

 the agreement is closest with Lycopodium, while in 

 some important details there is a nearer approach 

 to Selaginella, but of course the Lepidodendreae have 

 no near affinity with any of the modern genera. The 

 axis of the strobilus bore a very large number of crowded 

 sporophylls (or bracts, as they are often called), usually 

 arranged spirally, but occasionally verticillate. Each 

 sporophyll bore a single sporangium on its upper 

 surface. The sporangia were of large size, enormously 

 exceeding the dimensions of those in existing Lycopods. 

 Thus, in the magnificent specimen known as Lepido- 

 strobus Brownii, Schimper, the radial length of the 

 sporangia approaches 2 cm., with a maximum breadth 

 of about 5 mm. The great radial elongation of the 

 sporangia is characteristic of the genus, and is correlated 

 with the peculiar form of the sporophylls, which consist 

 of a long, slender stalk or pedicel, usually more or less 

 horizontal, terminating in a large lamina, which turns 

 vertically upwards, several sporophylls overlapping each 

 other. There is also usually a shorter downward 

 prolongation of the lamina, so that the form of the 

 whole is somewhat peltate (see diagram, Fig. 71). 

 The sporangium is attached all along its lower side 

 to the upper surface of the horizontal pedicel, but is 

 free from the lamina. In its form, and mode of 

 attachment to the sporophyll, the sporangium resembles 

 that of Iso'etes. 



The cones are often preserved as casts or impres- 



