54 WISCONSIN PHYTOPLANKTON 



Having a superficial resemblance to M. muricata (Bailey) Ralfs 

 but differing in that the lateral lobes all lie in the same plane, and 

 in the lateral projections of the polar lobes. 



14. MiCRASTERiAS MURICATA (Bailey) Ralfs. PI. 64, Figs. 4-5. 



Brit. Desm. 210. 1848; Wolle, Desm. U. S. 118, pi. 31, figs. 4-7. 1884; W. & 

 G. S. West, Trans, Linn. Soc. 2nd. Ser. Bot. 5: 239, pi. 14, figs. 5-6. 1896. 



Cells large, length about one and a half times the breadth, fairly 

 deeply constricted, sinus acute-angled at apex and then greatly 

 dilated, outer portion with widely open parallel sides, isthmus rela- 

 tively broad; semicells five-lobed, polar and lateral incisions very 

 broad and with rounded apices; polar lobe with basal portion broad 

 and rectangular, with upper portion greatly dilated and with the 

 angles continued in long slightly tapering cylindrical processes that 

 are upwardly curved and terminate in three or four minute blunt 

 conical spines ; polar apex convex, central portion with a conspicuous 

 narrow emargination and the lateral margins with a second pair of 

 asymmetrically disposed processes that are similar to those at the 

 polar angles; superior lateral lobes divided by an incision to form 

 two long horizontally disposed processes that lie above each other in 

 a front view of the semicell, processes arising from a conical base ; 

 inferior lobes submamillate, with the apex continued in a long cyl- 

 indrical horizontally disposed process, each process of inferior lateral 

 lobe with two similar but shorter processes, the three lying in the 

 same transverse plane at right angles to the long axis of the semicell, 

 all processes of lateral lobes with truncate ends bearing three or four 

 short blunt teeth. Cell wall smooth or finely punctate. Vertical view 

 oblong, sides somewhat tumid and angles continued in long, slightly 

 divergent processes, middle of each end with another similar process. 

 Chloroplast confined to the cell body but with fine laminate projec- 

 tions running into the processes, portion in the polar lobe entire, with 

 two conspicuous longitudinal ridges extending from the polar apex 

 to the nucleus and with curving ridges at the bases of the lateral 

 lobes; pyrenoids 12-15, confined to the body of the cell. (Tycho- 

 planktont.) 



Zygospores unknown. 



Cells 160-198 /A long; 110-130 jn broad at the inferior lateral lobes, 

 88-106 yu, broad at the superior lateral lobes, 86-96 ju, broad at the 

 apex of the polar lobes ; isthmus 22-23 /u, broad. 



Bass (rrr), Bettine (rrr), Carson (rrr), Jenny (rrr), Lindy (rrr), Little Doe- 

 tor (rrr), Nicaboyne (rrr). 



The species has much in common with Euastrum where it was first 

 placed by Bailey but it lacks the incision of the polar lobe and the 

 ornamentation of the cell body that characterizes Euastrum. There 

 is little danger of confusing it with other Micrasterias species. 



15. Micrasterias foliacea Bailey. PI. 65, Figs. 1-2. 



in Ealfs, Brit. Desm. 210, pi. 35, fig. 3. 1848; Wallich, Ann. & Mag. of Nat. Hist. 

 3 Ser., 5: 280, pi. 14, figs. 1-4. 1860; Wolle, Desm. U. S. 118, pi. 38, figs. 10-11. 

 1884; Johnson, Bot. Gaz. 19: 56, pi. 6, figs. 1-4. 1894. 



