60 ISOETACEAE (QCTLLWORT FAMILY) 



gynospores 486-720 n (average 600 /x) in diameter, sparingly covered with thick 

 vermiform subcoufluent or reticulated ridges except just beneath the equator ; 

 androspores 31-44 p. (average 36 /x) long, verrucose. Ponds 

 and lakes, N. S., Que., and Me. FIG. 26. 



4. I. foveolata A. A. Eaton. Polygamous ; leaves 50-150, 

 5-15 cm. long, 2 inrn. in diameter, round, pinkish or olive- 

 green ; sporangia thickly dark-spotted, ^ covered by the 

 G noTore x P 15 velum ; gy nos P ores 380-560 /x (average 44 J /x) in diameter, 

 the lower surface covered with little holes, the upper a 

 little more open ; androspores 22-35 /x long, reticulated or 

 papillose. Ponds and river borders ; N. H. and Ct. FIG. 

 27. 



Var. plen6spora A. A. Eaton. Leaves 30-110, 1.5 mm. 

 27 I foveolata. Gyno- * n diameter, 20-40 cm. long ; sporangia thickly dark-spotted, 

 spore x 15. \~\ covered by the velum ; gynospores white or ashy, 450- 



600 /x (average 510 /x) in diameter, covered with tall thin 

 mostly honeycomb-reticulated walls ; androspores 27-33 ft long, finely granular 

 or tuberculate. Gravelly shores of ponds in a thin layer of silt, s. e. Mass. 



5. I. riparia Engelm. Often polygamous; leaves 10-30, 1-3 mm. in diam- 

 eter, 10-25 cm. long, erect, dark green ; sporangia densely spotted, -J covered 

 by the velum ; gynospores 450-756 n (averaging 570 11) in diameter, covered with 

 high isolated, united, or reticulated jagged crests ; androspores 28-32 M (average 

 29 M) long, sparingly tubercled. Tidal shores of Del. R., in gravel. A species 

 misinterpreted in the past, and seemingly of restricted range. 



6. I. saccharata Engelm. Leaves 10-30, 1-2.5 mm. in diameter, 3-25 cm. 

 long, spreading or recurved ; velum very narrow to half covering the thickly 

 spotted sporangium ; gynospores 420-510 n (average 480 it) in diameter, covered 

 with low granules, reticulated walls or tall rough crests ; androspores 22-30 n 

 (average 28 /x) long, sparingly papillose. Fresh-water tidal flats, n. arm of 

 Chesapeake Bay and Del. R. Very variable and closely approaching the last in 

 some of its forms. 



Var. Amesii A. A. Eaton. Trunks 25-lobed ; leaves 8-30 cm. long, 1-1.5 mm. 

 in diameter, slender, finely pointed, quadrangular ; sporangia with few spots, 

 $-f covered by the velum ; gynospores 420-'300 /x (average 510 /x) in diameter, 

 marked with fine granules and thin short often reticulated walls; androspores 

 28-32 /x long. Gravelly shores overlaid by fine silt, chiefly in shallow water, 

 s. Mass, to N. Y. 



7. I. echindspora Dur. Leaves 10-30, 5-15 cm. long, 1.5-2 mm. broad, 

 dark green, finely pointed ; velum about one half covering the sporangium ; 

 gynospores 350-560 /x (average 500 11) in diameter, covered with simple or 

 forked spinules ; androspores 26-30 /JL long, smooth. Eu. A species repre- 

 sented in America by the following varieties. 



Var. Braunii (Dur.) Engelm. Differs from the type in having stomata on 

 the leaves, a broader velum, spotted sporangium, and not rarely broad jagged 

 crests on the gynospores. (Var. robusta Engelm.; /. B<-uttii 

 A. Br.) Muddy or sandy river and pond borders. Gaspe" 

 Co., Que. to B. C., s. to Cal. and Pa. ; variable. FIG. 28. 



Var. muricata (Dur.) Engelm. Submersed leaves 10-30, 

 flaccid, spiral. 15-40 cm. long, 1 mm. in diameter ; emersed l echinog ora 



ones 5-8 cm. long, slender, recurved ; sporangia pale-spotted, ,,nH Gvndspore 

 J| indusiate ; gynospores 400-620 ti (average 510 /x) in x 15 

 diameter, covered with slender round spines and flat, blunt, 

 or retuse lamellae; androspores 25-31 ft long, smooth or slightly granular. 

 Firm soil in shallow waters, mostly submersed ; N. S. to n. Me. and N. J. 

 Grades into the last. 



8. I. Eatbni Dodge. Polygamous ; leaves 30-200, 40-70 cm. long, 3-4 mm. 

 in diameter, flat above; stomata abundant; bast-bundles usually present; 

 velum very narrow ; sporangia densely light-brown spotted, not filled by spores ; 

 gynospores round below, upper half depressed, 300-450 /x (average 390 /x) in 

 diameter, with labyrinthiform-convolute ridges; androsporangia very rare, 



