6.3 



If the foregoing observations are correct the Puss and its 

 immediate allies would seem to constitute a limited and well 

 defined group of Moths whose larval development has reached a 

 high stage of specialisation and whose habits of feeding and rest 

 and the positions assumed at various stages of development show 

 a very delicate and still evolving adaptation to its needs. 



Azolia and Pilularia: two local Water Ferns. 



By W. Munn Rankin, M.Sc, B.Sc. 



Head before the Botanical Section, January 21 si, 1915. 



rpHE appearance in the early Spring of 191 4 of a species of 

 Azolia in Jumpers' Pond, near Iford Bridge, that well- 

 frequented resort of microscopists, suggests an account of its 

 distribution and structure as well as of the native water fern, 

 Pilularia. 



The Jumpers' Pond species is Azolia filiculoides. Another 

 species, A. caroliniana, also occurs in Britain, but the two are 

 readily distinguished by the fact that only A. filiculoides fruits 

 ' here. I am indebted for much of my information on the distribu- 

 i tion of these two species to a paper by A. S. Marsh in the 

 " Journal of Botany," Vol. LII. (19x4), b. pp. 209-213, and shall 

 I use it in the following notes on distribution. 



Azolia is a tropical and warm temperate genus, spread over 

 j both hemispheres. Two of the five species have been introduced 

 into Europe, and both have spread to our country: A. caroliniana, 

 a species of the eastern border of America with a range from 

 ! Ontario to Brazil, and A. filiculoides, which is confined to the 

 western part of America, between California and Chile. 

 A. caroliniana first appeared in Europe in 1872, when it was intro- 

 duced to Continental botanical gardens, from which it soon spread 

 into the neighbouring ditches and ponds and became a sort of 

 pest. It was first recorded for England at Pinden (Middlesex) in 

 1883, an d has since been recorded for other places in the South 

 of England, though in some cases in error for the other species. 

 It was not until Ostenfeld, of Copenhagen, while on tour with the 

 other botanists of the International Phytogeographical Excursion 

 of 191 1, identified the Azolia of Woodbastwick (Norfolk) as A. 

 filiculoides, that it was recognised that two species existed in 

 Britain. Azolia filicidoides was purposely introduced into Europe 

 in 1880 by Roze at Bordeaux, where he thought the marsh ditches 

 i were eminently suited for its growth. It rapidly spread on the 

 Gironde and later in the rest of France. It reached Italy in 1900. 

 j The exact season of its first appearance in England is not yet de- 

 1 termined, though it was distributed as A. caroliniana in 1910. It 



