90 BRITISH DESMIDIE^. 



16. E. binale (Turp.) ; segments concave or truncate at the end ; not 

 projecting beyond the acute angles. 



Jleterocmyella binalis, Turp. Diet, des Sc. Nat. par Levr. Alt. Vey. f. 14. 



(1820); Mem. du Mus. f. 17. Kiitz. Synop. Diat. in Linncea 1833, 



p. 598. Breb. Alg. Fal. p. 56. t. 7. 

 Cosmariiim binale, Menegh. Synop. Desmid. in Linncea 1840, p. 221. 

 Euastrum binale, Ralfs, Annals of Nat. Hist. v. 14. p. 193. t. 7. f. 7. (1844) ; 



Trans, of Bot. Soc. of Edinburgh, v. 2. p. 130. t. 11. Hass. Brit. Alg. 



p. 384. 



Penzance and Dolgelley, J. R. Henfield and elsewhere in Sussex ; Hamp- 

 shire, and Reigate, Surrey, Mr. Jenner. Hill of Rhoil (alt. 1 600 feet), Aber- 

 deenshire, Dr. Dickie. Near Aberdeen, Mr. P. Grant. Ambleside, Mr. 

 Sidebotham. Near Bristol, Mr. Thwaites. 



Falaise, Brebisson. New York, Professor Bailey. 



Frond very minute, about twice as long as broad ; segments inflated at the 

 base, either entire or bicrenate at the sides, slightly contracted upwards and 

 rather dilated at the end. The terminal notch is broad, and forms a concavity 

 between the angles. 



The variety ft. (which may prove a distinct species) differs in its quadrilateral 

 form and in its truncate ends, which have a small but distinct notch at the 

 centre. The acute angles are slightly prolonged horizontally ; the sides of the 

 segments are somewhat crenate, and the frond is rough, with a few scattered 

 and very minute granules. 



Euastrum biiiale is distinguished from the two preceding species by its con- 

 cave or truncate ends and its notch, the sides of which do not project beyond 

 the lateral spines or angles. 



A solitary conjugated specimen was gathered near Bristol by Mr. Broome, 

 but the sporangium was not completely developed. 



Length of frond (Tab. XIV. f. 8. c.) y^Vs" ^^ ^^^ ^^^^^^ ' breadth ^^^. : length of 

 frond (f. 8. d.) yyyg^ ; breadth y^g-g- : length of frond (f. 8. e.) xgVr 5 breadth 

 24-W: length (f. 8./.) yVor; breadth y^. 



Tab. XIV. fig. 8. a, c, d, e. fronds with endochrome ; b. empty frond ; 

 g. transverse view; h. a specimen conjugating; f. frond of var. ft. 



1 7- E. cimeatum (Jenner) ; segments cuneate, not lobed ; terminal 

 notch not linear. 



Euastrum cuneatum^ Jenner, in lit. cum specimine (1846). 



Aberdeenshire, Dr. Dickie. Dolgelley, J. R. Parham Old Park near Stor- 

 rington, Sussex, Mr. Jenner. 



The frond is larger than that of any other species in this section, and about 

 three times longer than broad ; the segments are nearly quadrilateral, broadest 

 at the base, and sloping upwards ; the ends are truncate, with a short linear 

 notch at the centre. The sides are not sinuated, and I have not detected any 

 inflated protuberances. 



The frond has so great a. resemblance to some states of E. crassum, that, 

 although its segments are not lobed, I think it may prove to be a variety of 



