1922] 



PFEIFFER — MONOGRAPH OF THE ISOETACEAE 201 



high, blade-like ridges, extending away from commissural ridges 

 on upper faces, somewhat incompletely reticulate above, irreg- 

 ularly reticulate basally ; microspores fawn-colored, 30-35 n long, 

 smooth. 



Distribution: Brazil. 

 Specimens examined: 

 Brazil: Prov. Minas Geraes, 22 January, 1874, 18 December, 



1864, RegneU ser. Ill 1506 (Gray Herb, and U. S. Nat. 



Herb.), type; Serra do Itatiaia, " in rivulo," 29 June, 1902, 



Dusen 643 (U. S. Nat. Herb.). 



58. I. Engelmanni A. Br. Flora 29. 178. 1846; Baker, Jour. 

 Bot. 18: 105. 1880; Motel. & Vendr. Actes Linn. Soc. Bord. 36: 

 374. pi. 12. jig. 1-9. 1883 ; Gray, Manual, ed. 4, 600. 1869 ; Clute, 

 Fern Allies, 233. 1905. 



/. Engelmanni var. gracilis Engelm. in Gray, Manual, ed. 5, 



677. 1867. 



/. Engelmanni var. jontana Eaton. Fern Bull. 13: 52. 1905. 

 /. Engelmanni var. valida Engelm. in Gray, Manual, ed. 5, 



677. 1867. 



/. valida Clute, Fern Allies, 236, 260. 1905. 



Corm 2-lobed; leaves 15-60 (100), 13-50 cm. long, light green; 

 stomata numerous; peripheral strands variable in number or 

 none; sporangia oblong, unspotted, with narrow velum; mega- 



spores white, 400-570 (615) u in diameter, distinctly marked 

 with honeycomb network of narrow ridges; microspores 21-30 \\, 

 seldom 33 u, in length, smooth to minutely roughened. 

 Distribution: eastern border to Mississippi Valley. 

 Specimens examined: 

 New Hampshire: "In a slight brooklet, dry most of the summer," 



in a forest, Seabrook, July, 1895, Eaton (Mo. Bot. Gard. 

 Herb.) ; millpond, in clay, Hampton Falls, August, 1895, 

 Eaton (Mo. Bot. Gard. Herb.) ; Coffin's Mill, 16 July, 1896, 

 Eaton (Mo. Bot. Gard. Herb.) ; mill-pond, Hampton 

 Falls, 1 August, 1896, Eaton (Mo. Bot. Gard. Herb.); 

 Powow River, South Hampton, 18 August, . 1896, 



Eaton 439 (Mo. Bot. Gard. Herb.); Trickling Falls, 



1896, Eaton (Mo. Bot. Gard. Herb.); East King- 

 ston, 28 July, 1896, Eaton 363-364 (Mo. Bot. Gard. Herb.) ; 

 flats at East Kingston, 6 July, 1896, Eaton 231 (Mo. 



