82 BRITISH DESMIDIE^. 



Frond oblong, and rather smaller than that of E. ohlongum. Segments 

 deeply five-lobed m a pinnatifid manner ; the terminal lobe is exserted, dilated 

 and emarginate ; the basal lobes are emarginate and the intermediate ones 

 smaller and entire ; the upper margins of all are horizontal. The transverse 

 Aaew is oblong, with three lobes or projections on each side and one at each 

 end. The empty frond is punctate, and the inflated projections are strongly 

 marked. 



Euastrum pinnatum somewhat resembles, but is smaller than E. ohlongum ; 

 the terminal lobe joins the others with a distinct neck ; the intermediate lobes 

 are always simple and smaller than the basal, and all the sinuses are more 

 romided. There is more difficulty in separating Euastrum affine ; still, when 

 it is compared with E. pinnatum the distinction is easily perceived, for the 

 latter is a larger plant, and is also distinctly five-lobed ; but in the former the 

 intermediate lobes resemble tubercles, as the sinuses between them and the 

 basal ones are much shallower. 



Length of frond y-^-g of an inch ; breadth at basal lobes ^iy ; breadth at 

 middle lobes -^\j ; breadth at end ^-i-g- ; breadth of neck y^Vr- 



Tab. XIII. fig. 1 . a. frond vdth endochrome ; b. empty frond ; c. side \aew ; 

 d. transverse view ; e. end view. 



5. E. humerosum, ; segments with terminal lobe dilated, emargi- 

 nate; neck partly included between the elongated middle lobes, 

 which resemble processes ; basal lobes emarginate. 



Dolgelley, J. R. New Forest, Hants, Mr. Jemier. 



Frond smooth, two or three times longer than broad ; segments sub-five- 

 lobed ; the basal lobes are emarginate ; the terminal one is dilated, its notch 

 linear, and the neck is short and partly included between the elongated pro- 

 cesses or tubercles which represent the middle lobes. The transverse \iew has 

 three lobes on each side and one at each end. The empty frond is minutely 

 dotted. 



Euastrum humerosum corresponds in size with E. affine, of which I formerly 

 considered it a variety, but Mr. Jenner finds that they differ essentially in the 

 transverse view. The present species is distinguished from all in this section 

 by its included neck. 



Length of frond -^\-g of an inch ; breadth of segment at base —^ ; breadth 

 at end -^ki 5 breadth of neck xxrg 5 lerigtb of projections at side of neck xsVt' 



Tab. XIII. fig. 2. a. frond with endochrome ; b. empty frond ; c. transverse 

 view. 



6, E. affine (Ralfs) ; segments three-lobed, with intermediate tubercles ; 

 lobes emarginate, the end one dilated, its notch linear. 



Euastrmn affine, Ralfs, A7inals of Nat. Hist. v. 14. p. 191. t. /. f. 3. (1844) ; 

 Trans, of Bot. Soc. of E din. v. 2. p. 128. Hass. Brit. Alg. p. 382. 



Dolgelley, J. R. Ambleside, Mr. Sidebotham. Sussex and Hampshire, 

 3Ir. Jenner. Aberdeenshire, Dr. Dickie and Mr. P. Grant. 



Falaise, France, Brehisson. 



