472 SMITH: ALGAE FROM THE LAKES OF WISCONSIN 
The type form, described by W. and G. S. West,* is nearly 
twice as large as the dimensions given above. The peculiar 
median constriction and the numerous chromatophores, however, 
show that the above described alga should be considered a variety 
of O. panduriformis W. West. 
TETRASTRUM APICULATUM (Lemm.) Brunnthaler 
Staurogenia apiculata Lemm. Bot. Centralbl. 76: 151. 1898; For- 
schungsb. Biol. Stat. Plén 7: 119. pl. z,f. 24. 1899; Schmidle, 
Ber. Deutsch. Bot. Ges. 18: 157. 1900. 
Tetrastrum apiculatum Brunnthaler; Pascher, Siisswasser-flora 
Deutschlands, Osterreichs und der Schweiz. 5:177.f.258. 1915. 
PLATE 24, FIG. 3 
I have observed this alga twice in the plankton of Lake 
Mendota. Some investigators follow Schmidle in placing Tetra- 
strum as a subgenus of Crucigenia Morren, but in my opinion the — 
two genera are distinct. 
CHARACIUM STIPITATUM (Bachmann) Wille 
Chlamydomonas stipitata Bachmann, Arch. Hydrobiol. u. Plank- 
tonkde. 3: 81. f. XP-—XI, 1908. 
Characium stipitatum Wille; Engler & Prantl, Nat. Pflanzenfam. 
1 (Nachtr.): 45. 1911; Brunnthaler in Pascher, Siisswassef- 
flora Deutschlands, Osterreichs und der Schweiz 5: 81. f. 26. 
IQI5. 
PLATE 24, FIGS. 4-6 
This peculiar species was previously known only from Scotland, 
where it was described asa Chlamydomonas species. I have found 
it in the plankton of three lakes, Minocqua, Pardee and Sishe- 
bogema, in the northern partofthestate. There is but little doubt 
that this is the same organism as that described by Bachmann, since 
the cell-shape and dimensions agree and it is only found epiphytic 
upon the same alga, Coelosphaerium Naegeliana Unger (Gom- 
bhosphaeria Naegeliana Lemm.). 
The alga is entirely enclosed by the gelatinous envelope of the 
Coelosphaerium colony and does not, as Bachmann describes, e 
merely have its stipe in the envelope. The figure copied by Brunn- 
* Jour. Roy. Micr. Soc. 1894: 15. bl. 2, f. 33-35. 1894. ; 
