BRITISH DESMIDIE^. 89 



15. E. elegans (Breb.) ; frond oblong; ends emarginate, pouting and 

 rounded. 



a. segments slightly constricted beneath the end lobe, ^vhich has 

 on each side a short horizontal spine. 



^.inerme', segments sinuated rather than lobed, and without spines. 



y. spinosum ; segments sinuated rather than lobed, and having 

 two or more spines directed obliquely outwards. 



Cosmarium eJegans, Breb. Menegh. Synop. Destnid. in Linncea 1840, p. 222. 

 Euastrum spinosum, Ralfs, Annals of Nat. Hist. v. 14. p. 193. t. 7. f. 6. 



(1844) ; Trans, of Bot. Soc. of Edinburgh, v. 2. p. 129. t. 1 1. Hass. 



Brit. AlgcE, p. 384. 

 Euastrum elegans, Kiitzing, Phycologia Germanica, p. 135 (1845). 



Common. Dolgelley, Carnarvon, Penzance, &c., J. R. Clieshunt, Mr. 

 Hassall. Barmouth, Rev. T. Salwey. Near Southampton ; Reigate ; fre- 

 quent in Sussex, Mr. Jenner. Ireland, Mr. Andrews. Hanham near Bristol, 

 Mr. Thwaites. Yate near Bristol, Mr. Broome. Cheshire and Westmore- 

 land, Mr. Sidebotham. Aberdeensliire and Banffshire (alt. 50 — 3000 feet), 

 Mr. P. Grant. 



Falaise, Brebisson. Germany, Kiitzing. New York, Bailey. 



Frond very minute, and about twice as long as broad ; the segments emar- 

 ginate at their sides, and the ends protuberant, rounded and emarginate. 



The sporangia are orbicular and spinous ; they have been gathered at Yate 

 by Mr. Broome, and by myself near Dolgelley. 



Euastrum elegans is a pretty but variable little species ; one state of it closely 

 approaches E. rostratum, with which it agrees in being somewhat contracted 

 beneath the terminal lobe, and also in its horizontal, though smaller, spines ; 

 but all its forms differ from that species by having the prominent ends not 

 angular but rounded. 



The variety ft. has no spines and no distinct neck ; the sides are undulated 

 rather than lobed, and the ends broadly rounded. 



The variety y. is distinguished by the spines being directed obliquely for- 

 wards, and besides those on the terminal portion it has usually one or two at 

 the sides ; there is no distinct neck, and the end is more protuberant and nar- 

 row than in the other forms. The spines of its sporangia are more nume- 

 rous and slender than those in the typal form. I have not seen sporangia 

 from a sufficient number of stations to decide whether differences in their spines 

 indicate different species ; but I beUeve that the number and shape of the spines 

 vary even in the same species. 



Length of frond of a. g-|-g- to ji-g- of an inch ; breadth yttt ^o 7^ ; dia- 

 meter of sporangium g-iy ; length of spine of sporangium 3^^^. Length of 

 frond of ft. -^^ ; breadth ^-i-j. Length of frond of y. -^\^ ; breadth y^g-g" '■> 

 diameter of sporangium ^4^ ; length of spine -^wsx- 



Tab. XIV. fig. 7. a, b, c. fronds of a. with endochrome ; d. sporangium ; 

 e. frond of var. ft ; /. mature frond of var. y ; g. side view ; //. transverse view ; 

 /", k. dividing fronds ; /. sporangium. 



