1922] 



PFEIFFER MONOGRAPH OF THE ISOETACEAE 173 



Reflection Lake, Mt. Rainier, 20 July, 1907, Cowles 776 (Mo. 

 Bot. Gard. Herb.); Lake Chelan, 22 September, 1897, Gor- 

 man 715 (Gray Herb.); in Bitter Lake, near Seattle, July, 

 1891, Piper 1117 (N. Y. Bot. Gard. Herb.). 



California: at alt. 8000 ft.,-, Mountain Lakes, head of Trinity 

 River, 1 September, 1882, Pringle (Mo. Bot. Gard. Herb., U. 

 S. Nat. Herb., and Gray Herb.) ; Castle Lake (near Scott's 

 Mountain), mountains about headwaters of Sacramento 

 River, scattered in gravelly bottom in 2-6 ft. water, 14 

 August, 1881, Pringle (Mo. Bot. Gard. Herb, and Gray 

 Herb.). 



42a. Forma robusta Pfeiffer, comb. nov. 



/. echinospora var. robusta Engelm. Trans. St. Louis Acad. 

 Sci. 4: 380. 1882. 



/. echinospora Braunii f. robusta Clute, Fern Allies, 221, 258. 

 1905. 



/. Gravesii Eaton, Fernwort Papers, 14. 1900. 

 I. valida var. Gravesii Clute, Fern Allies, 343. 1905. 

 Stouter than the species, with leaves as numerous as 75, 12-15 

 cm. long ; stomata usually numerous, more so than in the species. 



Specimens examined: 



Vermont: Lake Champlain, north end of Isle La Motte, 2 Sep- 

 tember, 1879, Pringle (Mo. Bot. Gard. Herb, and Gray 

 Herb.), TYPE; Lake Champlain, 19 July, 1878, Pringle (Mo. 

 Bot. Gard. Herb.). 



Connecticut: Tyler's Pond, near the outlet, W. Goshen, August, 

 1883, Underwood (Mo. Bot. Gard. Herb.) ; Tyler's Pond, W. 

 Goshen, August, 1889, Underwood & Cook (N. Y. Bot. 

 Gard. Herb.) ; gravelly and sandy tidal shores, Selden's Cove, 

 Lyme, 31 August, 1900, Graves (Mo. Bot. Gard. Herb, and 

 U. S. Nat. Herb.) ; same, Graves 145 (Mo. Bot. Gard. Herb.) ; 

 submerged, growing in mud, Selden's Cove, Lyme, 29 Aug- 

 ust, 1901, Graves (Mo. Bot. Gard. Herb, and Gray Herb.) ; 

 Selden's Cove, Lyme, 27 August, 1907, Eaton (Mo. Bot. 

 Gard. Herb.); shallow water of pond at Graystone, Ply- 

 mouth, 6 September, 1903, Bissell (Mo. Bot. Gard, Herb, 

 and Gray Herb.) ; Bristol, 1888, Bishop (U. S. Nat. Herb.) ; 



