ISOETACEM. 149 



* * Trunk trilobed ; velum nearly or quite complete. 



19. I. Nuttallii A. Br. Trunk almost globose, slightly- 

 grooved ; leaves 20 — 60, slender, bright-green, 3' — 9' long, with 

 only three peripheral bast bundles ; sporangia oblong or oval, 

 entirely covered by the velum ; macrospores v.iriable, 0.25 — 0.50 

 mm. thick, densely covered with minute but rounded warts, or 

 rarely almost smooth ; microspores papillose, brown, 0.025 — 

 0.028 mm. long. (/. opaca Nutt., /. Suksdorfii Baker.) Oregon, 

 Washington ; western Idaho [Geyir), Vancouver Island {Ma- 

 coun) ; California, (^ra«rf^o-«^). 



20. I. Orcutti A. A. Eaton. Trunk slightly trilobed, glo- 

 bose ; leaves 6 — 15, 2' — 4' long, 3" — 3I" broad, triangular, slightly 

 winged at base, with two weak bast bundles and rarely with 

 lateral ones ; velum entire ; ligula lunate or semicircular ; ma- 

 crospores very small, 0.24 — 0.32 mm. in diameter fuscous when 

 wet, cinereous or glaucous when dry, polished, the surface finely 

 pitted as with pin points ; microspores dark-brown, 0.022 — 0.035 

 mm. long, spinulose. On mesas at San Diego, California {Or- 

 cutt). 



21. I. minima A. A. Eaton. Trunk trilobed, iV' — 2" wide, 

 i" — i^" high; leaves 6 — 12, f — ij' long, slepder, with four peri- 

 pheral bast bundles; sporangia unspotted, 2" long; velum \ — f 

 covering the sporangium ; macrospores globose, 0.29—0.35 mm. 

 in diameter, covered with short, slender blunt spinules, the 

 equatorial commissure pectinate with polished spinules ; micro- 

 spores papillose or sparingly spinulose, white, 0.026 — 0.031 mm. 

 long. In damp places, Waverly, Spokane County, Washington 

 (Suksdorf). 



