BRITISH I>ESMID1E.K. 'JS 



about the same time by Mr. Jenner and myself. It may be distinguished at 

 first sight from all the preceding species by its smaller size, the gland-like ap- 

 pearance of the marginal teeth, the browner colour of the endochrome, and the 

 smaller and more crowded starch vesicles. It is more difficult to perceive the 

 puncta-like granules which border the sinuses. 



This plant agrees more nearly with M. apiculata, a species not yet detected 

 in Britain ; but in M. apiculata the endochrome is of a brighter green, and the 

 spines, which are scattered over the surface, are far more conspicuous. 



Length of frond from -^ to -^ of an inch ; breadth from ^ to ^ ; 

 diameter of sporangium -g-|^ ; length of spine y5^2- 



Tab. IX. fig. 1 . a. frond with endochrome ; b, c. empty fronds ; d and e. 

 end and lateral views from drawings by M. De Brebisson ; /. sporangium ; 

 ff. sporangium magnified 400 times. 



** Frond subelliptic ; segments three- or five-lobed ; lobes radiant, 

 the end one somewhat exserted and divergent. 



6. M. f areata (Ag.) ; segments five-lobed ; lobes bifid, their divisions 

 linear, divergent, and forked at the apex. 



Micrasterias furcata, Ag. Bot. Zeit. (1827). Kiitz. Synop. Biatom. in Lin- 

 ncea 1833, p. G03. Menegh. Si/nop. Desmid. in Linncea 1840, p. 216. 



Micrasterias Meliteyisis, Ralfs, in Annals of Nat. Hist. v. 14. p. 260. t. 6. 

 f. 2. (bad) (1844) ; Trans, of Bot. Soc. of Edinburgh, p. 132. 



Mici'asterias radiata, Hass. Brit. Freshwater Alg. p. 386 (1845). 



Hab. In a small pool a little below the outlet of Llyn Gwernan near Dol- 

 gelley, also in the stream that issues from the lake : very rare, /. R. 



Worden's Pond, Rhode Island, Bailey. 



The frond is smaller than that of M. rotata ; its outline is broadly elliptic, 

 sometimes almost circular. Each segment is deeply five-lobed ; all the lobes 

 are bifid and their subdivisions linear and forked at the extremity, the forks 

 being usually incurved. The end lobe is broadest and somewhat exserted ; 

 its divisions are more divergent and the sinus more rounded than in the lateral 

 lobes. The endochrome is green with scattered starch vesicles, and seldom 

 extends beyond the bifurcation of the lobes. 



M. furcata bears some resemblance to M. Crux-Melitensis, but is far more 

 elegant, its incisions are deeper, its divisions more slender, and the terminal 

 notch is incurved in a forceps-like manner. 



Length of frond yir of an inch ; breadth -^^. 



Tab. IX. fig. 2. a. frond with endochrome ; b. empty frond. 



7. M. Crux-Melitensis (Ehr.) ; frond rotundato-elliptic ; segments 

 sub-five-lobed ; lobes bifid, subdivisions short, stout and bidentate 

 at the apex. 



Euastrum Crux-Melitensis, YAw. Abh. d. Berl. Ah. p. 82 (1831); Infus. 

 p. 162. t. 12. f. 3. Pritch. Infus. p. 196. f. 124. Bailey, Amer. Bacil. 

 t. I. f. 23. 



