SPECIES OF ALG^. 51 



b. Outer circle 14, inner 7, centre closed by i; outer spaces 7, inner 4, 



simplex var., 153 



b. Outer circle 12, inner 4, centre open; outer spaces 4, 



duodenarius, 153 



b. Outer circle 14, inner 7, centre closed by 4; outer spaces 7, inner 4, 



simplex var., 153 



c. Marginal cells 2-lobed, each cuspidate; cells 8-16-128; centre closed, 



Boryanum, 153 



d. Perforated by small openings ... . brachylobum, 154 



d. No openings; centre closed; . . muticum, angulosum, 153 



e. Perforate by small openings, or centre open (/). 



e. Not perforate, centre closed {g). 



f. Cells 16-32-64 . . . 

 /. Cells 6, centre open . 



g. Apices converging, space between oval 

 g. Apices not converging (li). 

 h. Each apex 2-lobed, sometimes diverging 



pertusum, 154 



angulosum, var., 154 



forcipatum, 153 



Ehr enter gii, 154 



utriculatum, 169 



microporum, 170 



cambricum, 170 



spinulosum, 171 



cruaatum. 



41. HYDRODICTYON. 



One species 



42. CCELASTRUM. 



a. Cells globose, with interstitial openings . . 

 a. Cells angular, each with a tubercular process 



43. SORASTRUM. 



One species 



44. STAUROGENIA. 



One species . . 



45. SCENEDESMUS. 



§ Cells armed with spines (a). 

 § Cells not armed with spines {e). 

 a. Aquatic (b). 



a. On moist sand, Florida; cells 2-4, fusiform, 



antennatus, var. recites. 



b. Cells oblong, cylindrical, ovate or globose (c). 



b. Cells, some at least, spindle-shaped [d). 



c. Spines recurved on outer cells 

 c. Spines straight, single or sometimes two 



c. Spines straight, three to five 



d. Inner cells fusiform, armed, outer lunate, 

 d. Fusiform, oval or globose; spines straight 



171 



172 



caudatus, 172 



polymorpkus, 173 



. rotundatus, 174 



dinwrphus, 173 



polymorpkus, 173 



