DKSMIDS FLORA OF MICHIGAN 
261 
Specimens of this forma collected in Roscommon County 
appear to bc intermediate between A’, antilopaeuni var. Craineri 
Grônbl. (Grônblad 1921) and A', mauricianum (Irénée-Marie 
1949b). The single spine at the basal angle is characteristic of 
A. cristatiim Bréb. The sha]ie of lhe semicells and the single 
convergent spine at the basai angle are similar to X. ntaiiricia- 
niim although the semiccll outline is definitely hexagonal, 
Irénék-Marie’s species being almost rectangular. The central 
facial area of the seinicell wall lias a three-ipiarter row of 
scrobioulations that is also found in A’, antilopaeiun var. Crameri 
Grônblad. The paired sjiines on the latéral angles, however. easily 
separate the Michigan form from his variety. The general semi- 
cell shapc and the sharp convergence of lhe suprabasal margins 
lowards the basal angles distinguishes this form from A', crista- 
ium. The hexagonal shape of the semicells and the similarity 
of the facial scrobiculations with var. Crameri makes rétention 
of this form in A’, aniilopaeum necessary despite lhe occurrence 
of a single basal spine as in both A’, cristatum and A', mauricia- 
nnm. 
X. aniilopaeum var. basiornainm Eichl. and Racib. Schoolcraft 
County. New record for Norlh America. 
A’, antilopaeiim var. oligacantbnm Schmidle. Emmet County. 
A', aniilopaeum var. triquetrum Lund. Delta County. This is the 
only record for North America except for a report of this variety 
by Wajles (1988) in British Columbia. 
A. cristulum var. hipparqiiii Irénée-Marie. Calhoun County. 
A. crislaliim var. papilliferum Irénée-Marie. Jackson, Marquette 
and Washtenaw Counlies. 
A. obsoletum Taylor. Specimens from Washtenaw County are 
lentatively placed here because lhey inay represent undeveloped 
individuals of an unknown species of Xanthidinm. The projec¬ 
tions from the angles were short, usually blunt, knob-like spines 
in contrast to the short incrassate projections found in A. obso- 
lefum. 
A. suhhasliferum var. johnsonii (West and West) G. M. Smith fa. 
nmilbii forma nob. (PI. 1, Fig. 9) {Xanthidinm subhastiferum 
var. johnsonii (West and West) G. M. Smith fa. Smith, 1924a. 
Wisc. Geo. and Nat. Hist. Surv. Bull. 57 (2) : 61, PI. 67, Fig. 7). 
Semicellülae subsemicirculares diia paria spinarum in margini- 
bus laleralibus habentes, spinis paris inferioris paulum ciirvalis, 
inter se paiilulum remoiis ac in planis verlicalibus differenlibus 
in maryinibus lateralibus, spinis paris siiperioris in anguHs api- 
calibus conferte insertis: regio superior centralis membranae 
semicellülae incrassaia atque scrobiciilata, scrobiculationibus in 
