166 THE AMERICAN MONTHLY [September, 



u. Processes long, horizontal teti-acerum^ 134. 



V. Processes curved, apices bifid pentad adu7n^ 139. 



v. " " apices entire iucis7i7n^ 133. 



V. Processes horizontally radiating; ends of cell with bifid papillae, 



peiitacertim^ 134. 

 V. Processes horizontally radiating; ends without bifid papillae, 



crenulatum^ 126. 

 V. Processes upwardly diverging, the apices bifid . . franconhim^ 131. 

 w. Diameter -g-i^ in. (40a) or smaller (a-). 

 ■w. " g-l-T) in. (70;/) or larger (j-). 



.r. Isthmus centrally ribbed ; rays curved downward . . comptinti^ 139. 

 x: '•'• not ribbed; in end view ravs basally separated by an acute in- 

 cision inc/'sum, 133. 



X. Isthmus not ribbed ; in end view rays separated by a rounded sinus, 



creniilatitm^ 126. 

 y. End \vith prominent papilhe ; diameter ^-^-^ to yL^ in. (140-150;/.) 



OpJiiura^ 134. 

 y. End with prominent papilhe ; diameter .,-/fj to g^ in. (75-8=;,'/). 



co7'onulat7ini^ I35* 

 y. End without prominent papilUe ; ray margins serrate, ?nacrocerum^ 134. 

 y. " '• '' ray margins granulate-crenate, 



hcxacerum^ 137. 

 z. End view oval, ends produced in a long, thin arm, . ungtilatutn^ 136. 



z. '•• fusiform, . ' fus/forfjie, 137. 



. z. End view triangular or 3-radiate {aa) . 

 z. "■ 4-radiate or angular {ce) . 



z. " 5-radiate ( ff") . 



aa. Apices of rays obtuse ; diameter gi^^ to -gl^g in. (40-50//.), aracJnie^ 139. 

 aa. " " '' diameter y^Vo to y^V^ "^- (15-20;/.), 



iotainnii, 137. 

 aa. Apices of rays not obtuse {bb) . 



bb. End of cell in front view papillose or verrucose (cc). 

 bb. '' " '' " not papillose nor verrucose )t/t/) . 



cc. Diameter -^\^^ in. (36;/.) or smaller, arciiattim, 139 ; subarcuatu?7i., 140. 

 cc. "■ 3!^ to yiyj^ in. (60-80;/.) ; arms diverging, . anatrnuifi., 139. 



dd. End view, sides straight, angles 3-4 spinous, . polymorphuni., 126. 

 dd. " sides concave ; arms long, straight, in front view diverging, 



paradoxum., 139. 

 dd. End view, sides concave ; arms short, HaabceJiense^ 131 ; na?i?tm, 138. 

 dd. '' sides convex ; arms short, tumid at base, Heleaimm., 133. 



ee. Apices of arms inconspicuously bifid or trifid, 



JIaab(xI/e//se, 131 ; pai'adoxtun., 139. 

 ee. Apices of arms prominent!}' and deeply trifid, .... Osceolense.* 

 ff. Apices of arms obtuse ; the arms mere lobes, very short, silatatum,i2d>. 

 ff. " " '' arms long, narrow, . . . arachne, 139. 



/f. Apices of arms bifid ; front view end with a crown of papillte, 



Florlde?ise., 135. 

 fp. Apices of arms bifid ; front view end without papillge, 



pentacladum., 136. 

 gg. End view 4, 5, 6, or 7-angular or radiate {////). 

 gg. End view triangular (//) . 



* Bulletin Torrey Botanical Club, Dec, 1885. 



