ISOETACE^. < 



crowding incident on this condition of the seedling plants the 

 elongate and slender leaves would naturally result." (Hist. Brit. 

 Ferns, ed. ii. p 302.) * 



Every one who has gathered I. eu-lacustris must be familiar with 

 this form, and to my eves I. Morei seems to be merely a greatly 

 developed state of this crowded form of I. eu-lacustris. No doubt, as 

 Dr. Moore says, in habit it resembles I. setacea Delille, and I. velata 

 A. Braun, but in the structure of the conn, of the leaves, and of the 

 velum it differs from these plants, and agrees perfectly with I. eu- 

 lacustris ; for both I. setacea and I. velata have the leaves furnished 

 with 6 peripherical bast-fibres. 



Dr. Moore says it differs from I. eu-lacustris "in the veil which 

 covers the macrosporangia being one-half longer, leaving only one- 

 third of the spores naked ;" but according to my experience the velum 

 in I. eu-lacustris does usually leave only one-third of the spores naked. 

 The macrospores seem quite similar in vars. a and /3. 



Attention was called to this remarkable form by Mr. A. Gr. More 

 in 1871, but it was not until November 1876 that Dr. Moore obtained 

 living specimens. These and some of the ordinary state he found 

 retained their respective character in cultivation. 



Lake QuiUwort. 



Subspecies II. — IsoeteS echinospora. Durieu. 



Plate 1827. 



Babenh. Crypt. Yasc. Europ. Ex. No. 76. Bab. Journ. Bot. 1863, p. 1. Milde, Filices 

 Europ. p. 279. 



Plant aquatic, submerged. Root-fibres glabrous. Conn 2-lobed 

 without longitudinal furrows, not clothed with the persistent and 

 hardened bases of former leaves. Leaves pellucid, pale green, sub- 

 cylindrical-terete or -subulate, with broad sheathing bases having 

 membranous margins and smooth backs, ascending, straight, without 

 marginal bast-fibres, and wuthout stomata (in the European plant). 

 Phyllodes absent. Teium incomplete. Sporangia subglobose oval- 

 ovoid. Macrosporangia with a white crustaceous integument, muri- 

 cate with very prominent acute spine-like tubercles, which are higher 

 than broad. 



In lakes in mountainous districts " where there is peat at the 

 bottom of the water." In a pool near Llyn-y-cwm near Llanberis 

 (Mr. W. Wilson) ; and in the river that runs out of the lakes of 



* Since the above was written I have seen Mr. Baker's monograph of the genus 

 in the ' Journal of Botany,' 1880, pp. 65 et seq. He considers I. Morei a form of 

 I. lacustris. 



