— 8i — 



Limpricht considers the genus Psilopilum well founded, and would 

 therefore not refer the plants in question to either Catharinea or Oligo- 

 trichum. But in deciding upon the specific name, he considers the fact that 

 Wahlenberg ignores the name imposed upon the plant by himself in 1803 

 sufficient ground to do so himself. Here Lindberg had the right view when in 

 1879 he restored Wahlenberg's first name, ranging the plant, however, under 

 Oligotrichum. We cannot but agree with Limpricht in accepting the genus 

 Psilopilum; but must differ from him when for so unacceptable a reason he 

 rejects the oldest specific name. The Psilopilum arcticum of Lesq. & 

 James' Manual should certainly be called Psilopilum g labratum (Wahlenb.), 

 Carl Miiller, following Hooker and the earlier view of Bridel, referred the 

 plant to Catharinea, which explains the above synonyms. Naturally, in de- 

 scribing the second species, this same author wrote Catharinea (Psilopilum) 

 Tschuctschica. But, under the influence of the other view this plant is simply 

 Psilopilum Tschuctschicum C. Miill., as the author himself writes it in his 

 Genera, p. 165. 



The absence of the crenulate margin toward the apex of the leaf was the 

 first intimation to the writer that this plant might be something different 

 from Psilopilu?n glabratum. Next it was noted that the spores vary from 

 24 to 36 in diameter, while Limpricht records 18-22 // as the size of the 

 spores in the old species. Through the courtesy of Mr. W. R. Maxon the 

 writer was able to see several specimens of authentic Psilopilum glabra- 

 tum. And through the especial kindness of both Miss Josephine Tildenand 

 Mr. W. R Maxon the original description of the second plant was made ac- 

 cessible. From this the above translation was made. 



It will b3 noticed that Carl Miiller emphasizes the distinctive character 

 of the cells near the leaf base: these are wider, rectaiigular in the new spe- 

 cies; narrower, ending in oblique walls, in the old species. In addition, the 

 cells of the exothecium are different in the two species: these are elongated 

 throughout the capsule in the new plant, but are mostly isodiametric, at 

 least near the middle of the capsule, in the old. Finally, the leaf costa 

 shows a characteristic difference: in the new plant there is a broad band of 

 several rows of stereid t-^Z/j under the dorsal band of thin walled large cells: 

 this is absent or quite inconspicuous in leaf sections of the old species. 

 Stem sections show no appreciable difference. 



While it was quite reasonable, and indeed to be expected, that a plant 

 occurring immediately on the west side of Bering Strait should also be found 

 on its east side, the writer decided, if possible, to make sure this determina- 

 tion by actual comparison with type material. This he was able to do by 

 the courtesy of Dr. S. Engler, who communicated a few plants of C. Miiller's 

 material from the herbarium of the Bot. Museum at Berlin. The compari- 

 son proves the North American plants typical Psilopilum Tschuctschicuin in 

 structure and size of parts. They show one unimportant difference, being 

 on the whole a little more compact than the type. 



Mr. Wm. R. Maxon, of the National Museum, furnishes the following 

 interesting data regarding the type locality, first collections, etc. 



