54 TI-FTS COLLEGE STUDIES, VOL. IV, No. 7 



Var. RETICULATUM Lagerheim, 1882, p. 56, PI. II, fig. i. 

 Colonies of 8-16 cells; all cells strongly emarginate, openings 

 large, rounded. Wis., G. M. Smith. Europe. 



Var. GRACILLIMUM W. & G. S. West, 18950, p. 52. Colony 

 up to 87 p. diani. ; cells very slender, marginal cells arcuate, 

 with two long, slender processes, emarginate at the apex ; other 

 cells 4-radiate, with very large openings. Wis., G. M. Smith. 



Page 179, after description of Var. EMARGINATUM, add, 



10. P. INTEGRUM Nageli, 1849, p. 96, PI. V. B. Disk con- 

 tinuous, rounded, cells 4-32, disk up to TOO /* diam., cells 

 usually irregularly placed, marginal cells differing little from 

 disk cells, 5-6-angled, 20-28 /* diam., marginal cells eacli with 

 two short, blunt, distant prolongations. Wis., G. M. Smith. 



Europe. 



11. P. KAWRAYSKII Schtnidle, i897a, p. 269; Brunnthaler 

 in Pascher, 1915, p. 103, fig. 63. Disk continuous, rounded, 

 disk cells often irregular, 5-6-angled, 10-12 /i diam. ; marginal 

 cells about 14 /* wide, with two rather large, smooth, straight, 

 truncate projections, not in the same plane, often crossing, 

 sometimes one or both wanting. Wis., G. M. Smith. Europe. 



12. P. SCULPTATUM G. M. Smith, 1916, p. 475, PI. XXV, 

 fig. 13. Disk oval or circular, 8-32-celled ; disk cells 4-6-sided, 

 with few openings ; marginal cells bilobed, the lobes produced 

 into divergent or parallel horn-like processes. Cell wall covered 

 with a network of very fine ridges; disk 80-150 /* diam., cells 

 10-15 /* Wis., G. M. Smith. 



13. P. ARANEOSUM Raciborski, var. rugulosum (G. S. West) 

 G. M. Smith, 1916, p. 476, PI. XXV, fig. 14; P. Boryanum 

 var. rugulosum G. S. West, 1907, p. 132, PI. V, fig. 22. Disk 

 1 50-200 /* diam. . cells 22-29 /A; margins of cells irregularly wavy, 

 surface with wavy ridges. Wis., G. M. Smith. Europe. 



Typical P. araneosum Raciborski, 1890, p. n, has not been 

 reported from America. 



14. P. GLANDULIFBRUM Bennett, 1892, p. 7, PI. II, figs. 5-7. 

 Colonies elliptical, continuous or with very small openings ; 

 marginal cells 5-6-angled, 10 p wide, 12 /* long, with a small 

 semicircular incision, with two projections from each cell, about 

 midway between side of cell and incision, projections about 15 n 

 long, filiform, distinctly capitate. Wis.. G. M. Smith. Europe. 



3. EUASTROPSIS Lagerheim, iSgsa, p. 20. 

 Colonies 2-celled, flat, in one plane, membrane thin and 

 smooth ; chromatophore a parietal disk with one pyrenoid ; 

 asexual reproduction by zoospores 2-many in a cell, formed by 



