1922] 



PFEIFFER — MONOGRAPH OF THE ISOETACEAE 135 



velum ; megaspores dark gray when dry, black when wet, 400-480 

 M in diameter, with small rough warts sometimes extended into 

 short narrow ridges, which rarely anastomose ; commissural ridges 

 thin and blade-like; microspores brown, 26-31 \i long, smoothish 

 to papillose. 



Distribution: Stone Mountain, Georgia. 



Specimens examined: 

 Georgia: shallow ponds on the summit of Stone Mt., May, 1869, 



Canby (Mo. Bot. Gard. Herb., Gray Herb., and U. S. Nat. 

 Herb.), type; St. Louis culture from Stone Mt. material, 

 13 August, 1875, Engelmann, (Mo. Bot. Gard. Herb.) ; top 

 of Stone Mt., April, 1875, Gray (Gray Herb.); cultivated 

 by Engelmann from young plantlets brought by A. Gray 

 from Stone Mt., 28 September, 1875, Engelmann (Mo. Bot. 

 Gard. Herb.); St. Louis culture (from roots brought from 

 Stone Mt. in September, 1876), August, 1877, Engelmann 

 195 If. (Mo. Bot. Gard. Herb.) ; shallow depressions on sum- 

 mit of Stone Mt., 13 April, 1897, ex Biltmore Herb. 4264 

 (Mo. Bot. Gard. Herb., Gray Herb., and U. S. Nat. Herb.) ; 

 shallow depressions on summit of Little Stone Mt., 15 May, 

 1897, Biltmore Herb. 4^64 & (Univ. Minn. Herb.); Stone 

 Mt., 17 April, 1891, Underwood (U. S. Nat. Herb.); "ma- 

 tured in laboratory" (from Stone Mt., 17 April, 1891), Au- 

 gust, 1891, Underwood (U. S. Nat. Herb.) ; "grown in lab- 

 oratory until December, 1891," (from Stone Mt., 17 April, 

 1891), Underwood (U. S. Nat. Herb.) ; top of Stone Mt., De 

 Kalb Co., 25 July, 1897, Eggert (Mo. Bot. Gard. Herb.) ; 

 "grown from Eggert's plants," 1898, ex Herb. Eaton (Mo. 

 Bot. Gard. Herb, and Univ. Minn. Herb.). 



30. I. lithophUa Pfeiffer, sp. nov. 1 



Corm 2-lobed, small; leaves 6-14 in number, 10-12 cm. long, 

 slender but not filiform, flexuous ; stomata numerous ; peripheral 

 strands variable, none or 3, weak ; ligule very small, cordate trian- 

 gular; sporangium 2.5-^4 mm. long, orbicular to oblong, com- 



*I. lithophila sp. nov. Cormus bilobatus, parvulus. Folia numoro 6-14, longitu- 

 dine 10-12 cm., gra cilia, flexilia, stomatibus mimerosis instructa, fibris ])« k ri])li^ricis 

 destituta vel tribus invalidis instructa. Lingula parvula, cordato-triangulata. Spo- 

 rangia longitudine 2.5-4 mm, orbiculata vel oblongata, velo completo. Macro- 

 sporae diam. 290-360^, madidae fuscescentes, siccac cineraceae, leves vel humili- 

 bus brevibus aliquantulum extentis jugis leviter ornatae. Microsporae coffeaceo- 

 fuscae, longitudine 30-33 /*, distincte tuberculatae vel spinulosae. 



