EUASTRUM. 33 



from the United States as " Euastrum mammilloaum" is a bad 

 illustration of a form of E. insigne. The plant that Wolle 

 figures as E. insigne is now known as E. orientale Turn. 

 Wolle never appeared to clearly understand the nature of 

 Euastrum insigne Hass. 



18. Euastrum intermedium Cleve. 

 (PL XXXVII, fig. 6.) 



Euastrum intermedium Cleve, Sverig. Desm. 1864, p. 484. t. 4, f . 1 ; Lund. 

 Desm. Suec. 1871, p. 21, t. 2, f . 4 ; De Toni, Syll. Alg. 1889, p. 1093 ; 

 Eichler, Mat. flor. Miedz. 1893, p. 61 ; 1894, p. 130; Eoy & Biss. Scott, 

 Desm. 1893, p. 177 ; West & O. S. West, Some N. Amer. Desm. 1896, 

 p. 242, t. 14, f . 18, 19 (forma) ; Nordst. Index Desm. 1896, p. 148. 



E. insigne b. intermedium Eabenh. Flor. Europ. Algar. Ill, 1868, p. 184. 



Holocystis intermedia Benn. Freshw. Alg. Eng. Lake Distr. 1886, p. 8. 



Helierella intermedia Kuntze, Revis. gen. plant. 1891, p. 898. 



Cells small, almost If times as long as broad, deeply 

 constricted, sinus widely open but narrowed at the 

 extremity; semicells three-lobed, with a large open 

 sinus between the polar and lateral lobes ; lateral lobes 

 obtusely conical ; polar lobe somewhat anvil-shaped, 

 angles acutely rounded, apex convexotruncate with 

 a narrow median incision ; semicells with two pro- 

 tuberances across the middle of the basal half (between 

 the two lateral lobes), and with two very small pro- 

 tuberances on the polar lobe, one on each side of the 

 median incision. Side view of semicell elongate- 

 pyramidate, with a protuberance on each side near the 

 base, lateral margins concave, and with a slight swell- 

 ing on each side of the apex, which is rounded (or 

 rounded-truncate). Vertical view elliptical, poles 

 acutely rounded, with two prominent protuberances 

 on each side near the middle; polar lobe elliptical, 

 with two slight swellings on each side near the middle. 

 Cell- wall smooth. 



Zygospore unknown. 



Length 54-68 /x ; breadth 31-40 p. ; breadth of 

 apex 20-26 p.; breadth of isthmus 9-10 /x; thickness 

 20-25 p.. 



ENGLAND. Cumberland (Bennett) . 



3 



