GO BRITISH DESMIDEACE.E. 



The specific name " Boldtii ; could not be used as it lias 

 already been utilised by Schmidle for a species occurring in 

 Germany, Russia, and Greenland. 



36. Euastrum pectinatum Breb. 

 (PI. XXXIX, figs. 10-12.) 



Heterocarpella pectinata Breb. in Cheval. Microscop. et usage, Paris, 



1839, p. 272 (name only). 



Cosmarium pectinatum Breb. in Menegh. Synops. Desm. 1840, p. 222. 

 Euastmm pectinatum Breb. in Ealfs' Brit. Desni. 1848, p. 86, t. 14, f . 5 a, 



b, d-f; Arch, in Pritch. Infus. 1861, p. 730, t. 2,f. 10, 30; Eabenh. Flor. 



Europ. Algar. Ill, 1868, p. 180; Kirchn. Alg. Scliles. 1878, p. 160; 



Cooke, Brit, Desm. 1886, p. 72, t. 34, f . 5 ; Hansg. Prodr. Algenfl. BOhm. 



1888, p. 204 ; De Toni, Syll. Alg. 1889, p. 1068 ; West, Alg. W. Ireland, 



1892, p. 138, t. 24, f . 7 ; Alg. Eng. Lake Distr. 1892, p. 723 ; Eoy & Biss. 



Scott. Desm. 1893, p. 177 ; Nordst. Index Desm. 1896, p. 197 ; West & 



G. S. West, Alg. S. England, 1897, p. 483 ; Alga-fl. Yorks. 1900, p. 65 ; 



Alg. N. Ireland, 1902, p. 28 ; Scott. Freshw. Plankton, I, 1903, p. 525. 

 Didymidium (Euastrum) pectinatum Eeinsch, Algenfl. Frank. 1867, p. 123. 

 Euastrum pectinatiim forma typica Boldt, Desniid. Gfronland, 1888, p. 6. 

 Helierella pectinata Kuntze, Eevis. gen. plant. 1891, p. 899. 



Cells of medium size, about 1^- times as long as 

 broad, deeply constricted, sinus narrow and generally 

 slightly open ; semicells three-lobed ; polar lobe dilated, 

 anvil-shaped, angles rounded, apex convexo-truncate 

 and slightly retuse in the middle ; lateral lobes sub- 

 quadrate, deeply retuse at the outer margin, angles 

 acutely rounded ; semicells with three large protube- 

 rances across the broadest part, and with two pro- 

 tuberances within the polar lobe (one on each side). 

 Side view of semicell widely inflated below, then con- 

 stricted and widening out into a dilated subtruncate 

 apex; angles of polar and lateral lobes bilobulate. 

 Vertical view elliptic-oblong, poles bimamillate, with 

 three large rounded-conical protuberances on each side ; 

 polar lobe elliptic oblong, poles bimamillate, and with 

 two rounded-conical protuberances at each side. Cell- 

 wall finely punctate (sometimes almost smooth). 



Zygospore globose or oblong-ellipsoid, furnished 

 with many elongated, blunt papillae. 



Length 69-73 ^ ; breadth 44-47 p. ; breadth of polar 

 lobe 32-35 \L ; breadth of isthmus 11*5-12 ^ ; thickness 

 33-36 /A; cliam. of globose zygosp. without papillae 



