138 Roosevelt Wild Life Bulletin 



This genus belongs in the subfamily of the Micractinieae and is 

 separated from the other members of the group by the stout append- 

 ages that do not terminate in a sharp point as well as by the solitary 

 spherical cells. The basal portion of the appendages shows a certain 

 similarity with those of Lagerheimia wratislazviensis Schrod., but the 

 apices and the stoutness of the processes are quite different. There 

 is also, a superficial resemblance between P. umbrinus and Ceras- 

 terias longispina (Perty) Reinsch but in the latter species the long- 

 processes are a continuation of the cell wall and not distinct 

 appendages. 



Schroderia setigera (Schrod.) Lemm. PI. 10, Figs. 3-5. 



In the discussion of the Wisconsin species of this genus attention 

 was called to a fine disc at the end of one of the terminal spines. 

 This was thought to be a character of all species of the genus but I 

 am now convinced that both the 5". setigera and 5". Judayi described 

 from Wisconsin lakes should be referred to a single species, 6". Judayi 

 G. M. Smith. The reason for this view is the discovery in Stahahe 

 Lake of an organism that agrees well with the original description of 

 S. setigera which states that there are simple spines at both poles of 

 the cell. The chloroplast of the New York specimens usually had 

 but a single pyrenoid, although some specimens were observed which 

 contained more than one pyrenoid ( Fig. 5 ) . 



Pediastrum biradiatum var. heterocanthum var. nov. PI. 12, 



Incisions in apices of lobes of marginal cells unequal, the interior 

 lobelets being much larger than the exterior. 



Cells 8 fx broad, 14 /* long; diam. of sixteen-celled 55 />i. 



Nigger Pond (rrr). 



The shape of the marginal cells suggests very strongly P. tetras 

 var. tetraodon (Corda) Hansg. but the interstices between the 

 interior cells and the lateral contact of marginal cells at the bases 

 only show that the alga should be referred to P. biradiatum Meyen, 



Micrasterias mahabuleshwarensis var. serrulata (Wolle) comb, 

 nov. PI. 16, Fig. 2. 



Micrasterias ringcns var. serrulata Wolle, Bull. Torr. Bot. CI. 12 : 128, pi. 

 51. fig. 15. 1885. _ _ 



This species is subject to considerable variation. The majority of 

 the individuals in Little Long Pond lacked the accessory processes on 

 the top of the polar lobe. With the exception of this feature the 

 variety agrees well with the type in shape and ornamentation of the 

 lateral lobes, central protuberance of the semicells, and shape of the 

 polar lobe. This variety may be considered identical with an organism 

 that Wolle describes as M . ringens var. serrulata but which seems in 

 a more natural place when considered a variety of M. mahabulesh- 

 warensis. 



Xanthidium subhastiferum var. Johnscnii (W. & G. S. West) 

 comb. nov. PI. 16, Figs. 6-7. 



Xaiithidhim hastifertiiii var. Johiisonii W. & G. S. West. Jour. Linn. Soc. Bot. 

 33 : 299. _ 1898. 



Xanthidium antilopaeum var. javanicum Johns, non. Nordst. Bull. Torr. 

 Bot. CI. 22: 295, pi. 239, fig. 10. 1895. 



