POLYSTICHUM. 87 



is divided ; and the spore-cases are borne along these 

 branches of the veins. The lines of sori on the pinnules 

 often become united into a mass, after they have been 

 some time developed, especially in parts where they are 

 rather crowded. 



Though a minute species, this Fern is widely scattered 

 over the face of the globe ; it is plentiful in many parts 

 of the south of Europe, and extends as far northwards as 

 Jersey. 



It grows readily, as an annual or biennial, sown on 

 sandy loam, and kept in a rather warm damp situation. 



Genus IV. POLYSTICHUM, or SHIELD FERN. 



- The group of Ferns formerly called Aspidium, or Shield 

 Fern, is now commonly divided into several lesser groups, 

 forming the modern genera. The English species of this 

 group are now classed under three genera, bearing the 

 names of Pohjstichum, Lastrea, and. Cystopteris. 



The P olysliclmms form a small and very distinct group 

 of evergreen Ferns, some forms of which rank among the 

 most beautiful of our native species. They once, along 



