I4 6 NATURAL HISTORY BULLETIN. 



Morong, Naiad. N. A., 41; Wats, and Coult., Gray's Man., 

 6th ed., 563; Upham, Fl. Minn.. 137. 



A graceful little plant with delicate, bright foliage, some- 

 what resembling P. -pusillus but larger. Rare in America. 

 Ponds and shallow lakes. July. 



Iowa Lake, Emmet county. Cratty; Muscatine, Herb. 

 Rep peri, No. 7 46 in part : Spirit Lake, Hitchcock. 



12. P. pusillus Linn. Spec. PL. 127 (1753). 



Morong, Naiad. N. A., 45; Wats, and Coult., Gray's Man., 

 6th ed., 563: Macmillan, Metas. Minn. VaL, 36; Hitchcock, 

 Ames FL, 522. 



A delicate species preferring shallow ponds and lakes. July. 



Ames, abundant at Cairo Lake, Hitchcock ; Muscatine, 

 Herb. Reppert, No. J 4.6 in part. 



13. P. spirillus Tuck. Am. Jour. Sci. and Arts, 2nd Ser., 

 VI , 226 (1848). 



Morong, Naiad. N. A., 49; Wats, and Coult., Gray's Man., 

 6th ed., 560; Beal and Wheeler, Fl. Mich.. 145; Bot. Death 

 VaL Ex., 210. 



This interesting little plant, not before reported from the 

 State, w r as collected in August, 1889, at Carnsforth, Iowa, by 

 Prof. Hitchcock, and again in July. 1894, by Mr. Kenneth 

 McKenzie in ponds along the C, R. I. & P. R. R., between 

 Muscatine and Fruitland. The specimens approach P. diver- 

 si folius Raf. | P. hybridus Michx.) in some characters, but are 

 quite clearly distinguished by the submerged spikes being 

 sessile or nearly so; by the broader submerged leaves, and by 

 the curious snail-like fruit which shows the coiled embryo 

 very conspicuously, even in the dried specimen. 



14. P. PECTIN ATUS Linn. Spec. PL. 127 ( 175^1. 



Morong. Naiad. X. A.. 51; Wats and Coult., Gray's Man., 

 6th ed., 504: Macmillan. Metas. Minn. VaL, 35; Arthur, Fl. 

 Iowa. 30. 



