4S4 Anxai.s of the Carnegie Museum. 



upper cauline leaves sheathing, bract-Uke : spikes 8-15 cm. long, 1.6- 

 2.5 cm. thick, obtuse, dense, many flowered ; bracts ovate, two thirds 

 as long as the flowers, apex elongate-acuminate : flowers sessile, white 

 or rarely somewhat yellowish, 1.4-1.9 cm. long, recurved-spreading ; 

 ovary and sepals minutely glandular-pubescent toward the base ; sepals 

 triangular-lanceolate, acute or somewhat obtuse, t.i-i.6 cm. long, 

 2-3 mm. wide ; lateral petals same length as sepals, oblong-lanceolate, 

 at the apex widely obtuse or sub-orbicular, more or less crenulate, the 

 lateral nerves forked toward the base ; lip 1.2-1.7 cm. long, 4-7 mm. 

 wide, somewhat clawed, more or less contracted at the middle, at the 

 apex obtuse or even orbicular, more or less laciniate, at the base 

 truncate- or cordate-orbicular, nerves forked ; callosities slender, in- 

 curved, at the base densely pubescent and more or less glandular 

 pubescent: capsules obovate-oblong, often curved, 1-1.4 cm. long. 



The type specimens, now in the Pennsylvania Herbarium of the 

 Carnegie Museum, were collected by the writer on Prcscjue Isle, Erie, 

 Pa., Aug. 24-26, 1905. The plants were quite abundant in the damp 

 sand surrounding the ponds in the more recently formed land at the 

 eastern end of the peninsula. In the herbarium of the Carnegie 

 Museum are other specimens of this species, collected also on Presque 

 Isle, August 16, 1S80, by Gustave Guttenberg, and a large bundle of 

 typical material collected September 9-1 1, 1900, by J. A. Shafer. 



The specific name iiicurviiin is given this species from the quite 

 strongly and sharply incurved callosities, a constant character, which 

 will at once serve to distinguish this species from Ibidium ccniiiuni 

 (Linnreus) House. Perhaps the most closely related species is the 

 more southern Ihidiiiiii oiioratum (Nuttall), which ranges from Vir- 

 ginia and Kentucky southward through the Gulf States, but the differ- 

 ences are, nevertheless, (juite marked between the two species. 



In order to more clearly contrast the diagnostic characters of Ibid- 

 ium inciirvnin with the other species of the genus occurring in the 

 northeastern part of the United States, the following key has been 

 worked out, mainly in accordance with the plan followed in Britton's 

 "Manual."' Recent studies in this genus by .Ames, " Contributions 

 Toward a Monograph of the American Species of Spiranthes ", - and 



' BriUoii, N. 1,., " Manual of the Flura ol the Northern -States and Canada," 2d 

 edit., 1905. 



i^Ames Oakes, " Orchidacea- : Illustrations and Studies of the Family Orchida- 

 cese," Fascicle I., 1905. 



