DESMIDS FLORA OF MICHIGAN 
269 
margins truncate with smooth broadly rounded angles, orna- 
mented with 3-4 traiisverse sériés of smal! granules; apices 
ornamentcd with row of short bifid ridges. Vertical view, semi- 
cells triangular, latéral margins straight or very slightly concave, 
angles truncate with smooth broadly rounded apices, ornamented 
w'ith 3-4 transverse sériés of granules, angles ornamented with 
a pair of lunate ridges just within inner concentric sériés of 
granules, each ridge accompanied inwardly by a shallow déprés¬ 
sion which is conspicuously punctate. Cell leiigth 20-21 jx, cell 
width 16-17 tj., isthmus 6.5-7 p.. Robinson Lake, Roscommon 
County. 
5. protectum var. plaiictoniciini G. M. Smith. Calhoun County. 
S. psendopachijryncbum Wolle. Alger County. 
S. punctulatiim var. pygmaeum (Bréb.) West and West. Calhoun 
County. 
S. qiiadrangulare var. armaium West. Oakland County. 
S. quebecense var. ornatum var. nov. (PI. 1. Fig. 8). 
Haec oarieias insîgnic praesentia in basi inflata semicelhilarum 
triuni ordinuni transuersorum granulorum paruorum vel ordinis 
iinici verrncarum tridentatarum, praesentia necnon diioruin gra- 
niilorum parvoniin vel spinanim in utroque margine laterali 
inter processus. Cellula M-à3 w. long., cuni spinis 4.9-55 a lat. 
îsthinus 10.5 y. lat. 
This variety can be dislinguished from the typical by the 
presence of three transverse rows of small granules or a single 
row of tridentate verrucae on the inllaled base of the semicells 
and by the presence of two small granules or spines on each 
latéral margin between lhe processes. Cell length 40-43 u., cell 
width with spines 49-55 y., isthmus 10.5 u. First Lake near Harris, 
Delta County and swamp next to County Park, Munising, Alger 
County. 
This organisni should be compared with illustrations of one 
identified by Dick (1919) as S. gracile var. coronnlatum Boldt 
which differs greatly from the illustration shown by West, 
West and Carter (1923), and with S. gracile var. splendiduin 
Messikommer (Messikommer 1928). The Michigan specimens 
ditfer from the former in the type of basal ornamentation, in the 
presence of the secondary apical latéral verrucae on the base of 
the processes and in the presence of a pair of short spines or 
granules on the latéral margins between the processes (rather 
than tridentate verrucae). It differs from the latter (S. gracile 
var. splendiduin) in the more pronounced basal inflation, in the 
basal ornamentation in the secondary apical latéral verrucae on 
the base of the processes and in the presence of a pair of short 
