OPHIOGLOSSUM. 209 



mature, the margin splits across at intervals corresponding 

 with the centre of each spore-case, so that eventually the 

 spike resembles a double row of gaping spherical cavities. 



The Adders-tongue is very abundant in the localities 

 where it is found, which are damp meadows and pastures, 

 on a loamy soil. It is generally distributed over England, 

 but is less abundant in the other parts of the United 

 Kingdom. The species is a common European plant, and 

 is found in North America as well as in Africa. 



There is no difficulty in cultivating the Adders-tongue, 

 whether in pots, or among an out-door collection of Ferns ; 

 the essentials are a stiff loamy soil, and the constant 

 presence of water enough to prevent drought. 



OpMoglossum lusitanicum, Linnams. 



The Dwarf Adders-tongue. (Plate XXI. fig. 3.) 



This species of Adders-tongue is technically distin- 

 guished by the small lanceolate and somewhat fleshy barren 

 branch of its fronds, and by its being altogether much 

 smaller than the common species. It may, indeed, be at 

 once known from that by this difference of size, as well as 

 by its difference of form. Tlie stem forms a short oblong 



P 



