OEGA.XS OF EEPBODUCTION. 



365 



The fructification of Salvinia {fig. 797) appears to resemble 

 that of Marsilea and Filularia, except that the antheridia, a, and 

 sporangia or ovules, h, are here contained in separate sacs, and 

 are attached to a sort of central cellular placenta {fig. 797). In 

 germination also, the prothallium of Salvmia differs from Mar- 

 silea and Pihdaria, in producing several archegonia, instead of 

 only one, as is the case with them. 



In reviewing the fructification of the Xarsileaceae, we find 

 that it differs from the Filices and Equisetaceae, in producing 

 two distinct kinds of spores, and in the prothallium not forming 

 a distinct expansion on the outside of the spore as is the case 

 with them, but being confluent with the spore. These cha- 

 racters show that the Marsileacese are nearly allied to the 

 Lycopodiaceae, which we now proceed to describe. 



4. Ltcopodiaceje or CLrB-5iossES. — The fructification in 

 this family is situated on the upper surface of the leaves at their 

 base {figs. 798 and 799). The leaves thus bearing the fructi- 

 fication are frequently collected together into a kind of cone or 

 spike {fig. 10), while at other times they are scattered along 

 the stem. The spores, like those of Marsileaceae, are of two 

 kinds, and are enclosed in separate cases. These cases are 

 variously named ; the names which would correspond to those 

 just used in describing the Marsileacese would be sporangia and 

 antheridia ; but the former are also commonly called oosporangia 



Fig. 798. 



Fig. 799. 



Fig. 800. 



Fig. 801, 



Fig. 798. Scale or leaf of SelagineUa apoda, with oosporangium or oopho- 



rldium in its axil. After Henfrey. Fig. 799. Pollen-sporangium or 



antheridium of the above, placed in the axil of a leaf or scale. After 



Henfrej-. Fig. SW. Pollen-sporangium of a species of Selaginella. It 



Is two-valved, and contains a number of small spores or microspores. 



Fig. 801. Oosporangium of aspecies of Selaginella. This is a two-valved, 

 four-lobed sac, and contains four large spores or ovules, called macro- 

 spores. 



