1922] 



PFEIFFER — MONOGRAPH OF THE ISOETACEAE 147 



Herb.), type; Mono Pass, in deep water, Bolander 6883 (U 

 S. Nat. Herb.). 

 There are two sheets of material, one with a single specimen 

 the other with two plants, in Mo. Bot. Gard. Herb., from Kneel- 



herbariu 



f 



that of /. Bolan deri, since they are very short and taper markedly 

 from a wide margin occurring at the sporangium level, but the 

 spore characters are very similar to /. Bolanderi. Additional 

 material from U. S. Nat. Herb, shows the same stout 



the 



probably from 



36. I. Tuerckheimii Brause in Urban, Symb. Antillanae 7: 

 161. 1912. 



Corm 2-lobed; leaves 10-31, 5-10.5 cm. long, slender, grad- 

 ually tapering to apex, with narrow membranaceous margin ex- 

 tending only to level of top of sporangium; stomata at tip of leaf; 

 peripheral strands none; ligule short- triangular, cordate at base; 

 sporangia globose to oblong, 3-4 mm. long, about 1/3 covered 

 by velum; megaspores 410-500 \i in diameter, smooth or lightly 

 marked with rather distant low warts; microspores 26-32 \i long, 

 smooth. 



Distribution: Haiti. 



Specimens examined: 

 Haiti (St. Domingo); near Constanzo in Valle Nuevo, alt. 2200 



m., in rock fissures in rivulet, August, 1910, Turckheim 



3531 (Mo. Bot. Gard. Herb., Gray Herb., N. Y. Bot. Gard. 

 Herb., and U. S. Nat. Herb.), type. 



Of the available species /. Tuerckheimii seems to resemble in 

 spore characters /. mexicana Underw. Jt differs in the lack of 

 peripheral strands and in the very different habitat. 



37. I. mexicana Underw. Bot. Gaz. 13 : 93. 1888. 



/. Montezumae Eaton, Fern Bull. 5: 25. 1897. 



Corm 2-lobed; leaves 10-30, 7-23, or rarely 30, cm. long, fine, 

 erect, tapering, with membranaceous margin 2-3 times length of 

 the sporangium; stomata numerous; peripheral strands usually 

 4; ligule triangular, somewhat elongated; sporangia 3-6 or even 

 8 mm. long, with very narrow velum; megaspores white, 320- 



