WISCONSIN PHYTOPLANKTON 101 



Cells 42-48 jn long with processes, 32-34 /a long without processes ; 

 breadth with processes 69-86 fi, without processes 20 fi ; breadth at 

 isthmus 8.5-9 jj. ; thickness 14 [x. 



Tank (rrr). 



Superficially the species resembles S. Johnsonii W. & G. S. West 

 but differs in the parallel processes, lack of subapical and istlimial 

 ornamentation, termination of the processes, and shape of the semi- 

 cells. Nordstedt's figure shows five elevated verrucae in the front 

 view but in all of the specimens that I have seen there are only three. 

 The shape of the semicells, especially the small body of the cell in a 

 vertical view, and the branching of the ends of the processes show 

 that the organism which I have found is 8. grallatorium. The 

 processes do not end in spines as do the other biradiate species of 

 the genus, instead the process ending is bifurcate and distinctly hol- 

 lowed. 



var. FORCiPiGERUM Lagerheim. PL 77, Figs. 6-7. 



Ofvers. kgl. Sv. Vet.-Ak. Forh. 42, No. 7: 249, pi. 27, -fig. 27. 1886. 



Staurastrum saltans var. forcipigerum Lagerheim, ibid. 44, No. 8: 539. 1887. 



Semicells trapeziform, with apex truncate and bearing two elongate 

 subapical verrucae, apex with two fairly long divergent spines 

 asymmetrically disposed on the sides of the elongated median por- 

 tion; processes with margins more coarsely crenulate and with fewer 

 crenulations, furcation of ends of processes unequal, the fork on the 

 side towards the isthmus always the longer. (Tychoplanktont.) 



Cells 45 fi long with processes, 38 ju. long without processes; breadth 

 with processes 65-72 fx. ; without processes 21-25 [i ; breadth at isthmus 

 7.5—8.5 jLt. 



Hillman (rrr). 



After describing the alga as a variety of ;S^. grallatorium Lagerheim 

 transferred it to 8. saltans Joshua, an alga which was not correctly 

 figured until some years later (W. & G. S. West, Trans. Linn. Soe. 

 2nd. Ser. Bot. 6: 188, pL22, /i^s. 13-14. 1902). Mr. Charles Bullard 

 has shown me a preparation in which one semicell is typical 8. gralla- 

 torium and the other the variety forcipigerum. From this it is evi- 

 dent that if the variety is to be recognized it belongs to 8. gralla- 

 torium. 



39. Staurastrum anchora W. & G. S. West. PI. 77, Figs. 8-9. 

 Trans. Linn. Soe. 2nd. Ser, Bot. 5: 266, pi. 17, figs. 21-22. 1896. 



Cells large, breadth (with processes) twice the length, slightly con- 

 stricted, sinus sublinear, isthmus relatively broad; semicells cam- 

 panulate, with bases slightly inflated, apices flattened and smooth; 

 angles of semicells prolonged in long somewhat tapering processes 



