SPH^RELLA V. MYCOSPH^RELLA 



89 



IX. — A New Species of Euastrum. 



Euastrum laticolle, sp. n. E. submediocre, circiter 1^-plo 

 longius quam latum, profundissime constrictum, sinu angustissimo- 

 lineari ; semicellulae trilobae, incisuris inter 

 lobas late concavo-excavatis ; lobis lateralibus 

 trapeziformibus, angulis superioribus et inferi- 

 oribus leviter rotundatis, lateribus sursum diver- 

 gentibus et levissime retusis ; lobo polari trans- 

 verse subrectangulari, angulis vix rotundatis 

 paullo productis, apice convexo sed retuso in 

 medio ; in centro semicellularum et prope isthmo 

 tumore parvo instructo. A vertice visas trans- 

 verse subhexagono-rectangulares, tumore sub- 

 conica ad medium utrobique, polls concavis, 

 angulis polaribus duobus rotundatis, lateribus 

 inter tumorem centralem et angulos polares 

 late concavis; lobo polari transverse subrectan- 

 gulari, angulis subrotundatis et lateribus leviter 

 concavis. Membrana irregulariter et subsparse 

 punctulata. Long. 58 ix ; lat. 44 fx ; lat. lob. 

 polar. 26 />i ; lat. isthm. 10 /x ; crass. 30 /x. 

 (Pig. 6.) 



Hah. In a bog at Lindeth, near Bowness, 

 Westmoreland. 



This is a very distinctive species, its only near relative being 

 E. Berlini Boldt (in Bib. till K. Sv. Vet.-Akad. Handl. Bd. 13, 

 1888, p. 10, t. 1, f. 12), a Desmid known only from Gronnedal in 

 South Greenland. From this Arctic Desmid E. laticolle differs 

 in the form of the front view, having a closed and linear sinus, 

 and lateral lobes of quite a different shape. The general outline 

 of the vertical view is the same as in E. Berlini, but in the latter 

 species the polar lobe is described (and also figured) by Boldt as 

 "late elliptico" when seen in end view, whereas that of E. laticolle 

 is rectangular with retuse sides and rounded angles. 



Fig. 6. — Euastrum 

 laticolle, sp.n., x 500, 

 A, front view; B, 

 vertical view. 



SPH^BELLA V. MYCOSPEuEBELLA. 

 By W. B. Grove, M.A. 



The genus Sphcerella was founded by Sommerfelt in 1824 for 

 a group of algae belonging partly to the Volvocales. In 1828, 

 Agardh established the genus Hcematococcus, which included one 

 species of the same group. Again, in 1849, the name Sphcerella 

 was given by Fries to a subgenus of Sphceria, among the Pyre- 

 nomycetes, which was afterwards raised by Cesati and de Notaris 

 to the rank of a genus. So long as it was the custom to use 

 Hcematococcus for the algal genus, the name Sphcerella could be 

 legitimately employed for the fungal one, and over five hundred 

 species have been described under that title. But when the word 



Journal of Botany. — Vol 50. [March, 1912.] h 



