ALLOSOEUS. 63 



and attains great luxuriance in a damp hot-house. The 

 proper soil for it is very light turfy peat, mixed with a con- 

 siderable proportion of silver sand, and it is beneficial to 

 plant it on or around a small lump of free sandstone. 



Genus IT. ALLOSOEUS, Bernhardi. 



OF this family we have but one British species, the Allo- 

 sorus crispus. It is known from all its fellow-country-ferns 

 by the coincidence of the following features. It bears fronds 

 of two kinds, one being leafy and barren, or without sori, 

 the other contracted, and bearing sori, and hence called 

 fertile. The edges of the lobes of the fertile fronds are 

 rolled under (which is what gives them the contracted ap- 

 pearance), and covers the sori in the stead of a special in- 

 dusium ; the sori when young form distinct circular clusters 

 beneath this recurved margin, but as they grow they join 

 laterally (in technical language, they become confluent), 

 forming two lines of fructification lengthwise the segments 

 of the fronds. 



The name Allosorus is compounded from the Greek, and 

 comes from alias, which means various, and sorus, which 



