ALLOSORUS. 83 



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

 are rolled under (which is what gives them the contracted 

 appearance), and cover the sori in the stead of a special 

 indusium ; 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 alios, which means various, and sorus, 

 which means a heap : the intention probably being to 

 indicate the variation or change which occurs in the appa- 

 rent arrangement of the sori, from the distinct patches to 

 the continuous lines in which they are seen to be disposed, 

 if examined at different stages of development — the change, 

 after all, being only apparent, and not real. The name, 

 however, may have been intended to express the variation 

 in the character of the sorus in the different species origi- 

 nally assigned to this genus, 



Allosorus crispus, Bernhardi. 



The Rock Brakes, or Mountain Parsley. (Plate V. fig. 1.) 



This elegant little plant, which has considerable first- 



G 2 



