332 STUDIES IN FOSSIL BOTANY 



The size of the individual sporangia is somewhat 

 smaller than in Renault's Zygopteris, their length ranging 

 from 1.5 to 2 mm., and their maximum diameter from 

 .7 to 1 mm. The essential difference, however, from 

 the sporangia of Zygopteris is in the annulus, which in 

 Botryopteris was limited to one side of the capsule, 

 where it formed a broad, oblique band of thick-walled 

 cells (Fig. 123). The spores, except for their somewhat 

 smaller size, agree exactly with those of Zygopteris, and, 

 curiously enough, the same two states of the spore, 

 already discussed in the case of that genus, recur here. 



In one case a group of sporangia was found to be 

 associated with a very curious envelope or indusium, of 

 complicated structure, which M. Renault regarded as 

 derived from a zone of sterile and highly modified 

 sporangia. 



It may be mentioned that the English specimens of 

 B. hirsuta and ramosa are found associated with 

 numerous sporangia, which appear to have essentially 

 the same structure as those of the French species, but 

 are of much smaller size. It is extremely probable that 

 they represent the fructification of the English repre- 

 sentatives of the genus. The association is close and 

 practically constant, and as these species are among the 

 commoner coal-ball fossils, this fact is of great weight. 

 In one case the sporangia, which appear to have already 

 dehisced, are found grouped on a rachis, as in Renault's 

 specimens (see Fig. 124). They are, in the common 

 form, of roundish shape, 350-400 /j, in diameter, with a 

 broad band of enlarged cells on one side, comparable to 

 the false annulus of Osmundaceae (see Fig. 125). The 

 somewhat triangular spores are characteristic. 



