172 THE JOURNAL OF BOTANY 



Eleutherosphsera, n. g. — Perithecia subglobosa, ostiolo longo 

 subulato, diaphana. Asci fusoidei. Sporidia fusoidea, hyalina, 

 septata. 



Explanation of Plate 485- 



Fig. 1. — Dasyscypha canescens — a, cup x 50 ; 6, asci, paraphyses and spores 

 X 500 ; c, Acrotheca canescens x 100 ; d, hjiphse and conidia x 500, 



Fig. 2. — Coryne urnalis — a, immature ascus and paraphyses x 600 ; 6, 

 ascus dehisced at apex; c, mature ascus, containing four megaspores and about 

 a hundred microspores, flattened by pressure of cover -glass; d, spores, face- 

 view below, profile-view above ; e, hyphae and conidia x 600 ; /, group of all 

 three kinds of spores x 600. 



Fig. 3. — Eleutherosphcera longispora — a, perithecium x 250; b, ascus with 

 spores x 250 ; c, ostiole of perithecium x 600 ; d> unripe spore, e, mature 

 spores x 600. 



FORMS OF POTAMOGETON NEW TO BRITAIN. 



By Arthur Bennett. 



1. Potamogeton vaginatus Turcz. " Foliis omnibus submersis 

 membranaceis pellucidis, basi vaginantibus lineari-setaceis acutis 

 trinerviis, venis trans versis destitutes ; vaginis laxis ; spicis longe 

 pedunculatis, floribus interrupte verticillatis ; fructibus oblique 

 obovatis, seniiorbicularibus compressis, siccatis dorso obtusis, medio- 

 que stria tenui percursis. 



u P. vaginatus Turcz. Cat. Baic. Dah. n. 1092. 



11 Prater notas indicatas a prsecedente [P. pectinatus] , quocum a 

 beato Ledebourio injusteconjunctum fuit, habitu robustiore dignos- 

 citur." Turczaninow in Fl. Baicalensi-Dahurica, ii. 2, 162 (1856). 



P. pectinatus Ledeb. Fl. Ross. iv. 31 (1853), (pro parte). 



P. pectinatus /3 fluviatttis Schiibler & Martens, Fl. Wurtemb. 112 

 (1834), teste Hochreutiner in Bull. Herb. Boiss. v. 12 (1897). 

 A. O. Kihlman in Meddel. Soc. Fauna et Flora Fenn. xiv. 

 110 (1887). 



P. pectinatus L. subsp. vaginatus Magnin in Bull. Soc. Bot. Fr. 



xliii. 447 (1896). Neuman & Ahlfvengren, Sveriges Fl. 793 

 (1901). 



Distribution. Europe: Sweden 1 Archangel, Russia ! Switz- 

 erland ! Austria ! Mecklenburg ! Finland ! Asia : Turkestan ! 

 Songaria ! Irkutsk, Turczaninow ! N. America : Labrador, Waitz ! 

 in herb. Boissier. Assiniboia, Macoun ! Buffalo Lake, lat. 56° ! 

 Extends north to 64° ; Bygdea, Gulf of Bothnia, and in Finland 

 to 66°, Haaparanta : Hartm. Skand. Fl. ed. 12, 55 (1889). The 

 plant probably occurs in other parts, but its distribution is as yet 

 imperfectly worked out. Great Britain: Shetland (co. 112) ; Ting- 

 wali Lock, in Scalloway, Mainland (W. H. Beeby sp. !), Aug. 1887. 



Differs from pectinatus in the loose ample sheaths of the lower 

 leaves, the leaves (always?) without transverse veins, the first 

 smaller, more compressed, and in many the keels are almost obso- 

 lete. I possess the plant from fourteen stations, and have seen it 



