146 



In the preparation of this paper I am especially indebted to Dr. P>. L. 

 Robinson, curator of the Gray Herbarium, for the loan of the speci- 

 mens of Nissolia, Waltheria, and of miscellaneous specimens in his 

 charge; to Mr. J. M. Greenman, of the Gray Herbarium, for various 

 critical notes and comparison of specimens; to Mr. John Donnell Smith 

 of Baltimore, for the loan of his specimens of Waltheria and Nissolia; 

 to Mr. E. G. Baker, of the British Museum, who has verified most of 

 my identifications in the Malvaceae and has assisted in the preparation 

 of some of the notes and technical descriptions. Besides this assist- 

 ance, Mr. George E. Davenport, of Medford, Mass., has kindly deter- 

 mined my collection of ferns. Mr. William K. Smith, superintendent 

 of the Botanic Garden at Washington, has courteously placed at my 

 disposal the valuable facilities of that institution. 



FERNS COLLECTED IN MEXICO BY J. N. ROSE DURING THE 

 MONTHS OF AUGUST AND SEPTEMBER, 1897. 



By George E. Davenport. 1 



ACROSTICHUM. 



Acrostichum conforme Sw. Syn. Fil. 10, 192, t. l,fig. 1. 1806. 



Santa Teresa, Territory of Tepic, August 12 (No. 2215). 



A small plaut with ovate-elliptical fronds, apparently identical with A. obtusi- 

 folium Brack. Heller's No. 2808 iu the Gray Herbarium at Cambridge, Liebmanns 

 No. 7, and Pringle's No. 491(5, referred to this species, have a more delicate, slender 

 rootstock, and may be different. 



The species is an extremely variable one, and some of the smaller forms are diffi- 

 cult to place without the aid of a good series of specimens. 

 Acrostichum pilosum II. IS. K.; Willd. Sp. PL 5: 103. 1810. 



Sierra de los Morones, near Plateado, State of Zacatecas, September 1, 1897 (No. 

 2728); also Santa Teresa, August 12, 1897 (No. 2210). 



The latter consists of smaller plants, quite different in appearance, but apparently 

 the same as No. 2728; the scales of the rootstock, stipes, and costa- are identical, as 

 is the form of the lamina. The two arc not safely separable. 

 Acrostichum spathulatum Bory, Voy. Mers d'Afriq. 1 : 303, /. BO, fig. 1. 1804. 



Santa Teresa, Territory of Tepic, August 12, 1897 (No. 2202). 



Specimens all sterile and not as tibrillose as Pringle's No. 4964 from San Felipe, 

 Oaxaca, 1894, or No. i:006 from near Guadalajara, 1889, but not safely placed else- 

 where. The specimens closely resemble Bourgeau's No. 3072 from Orizaba, 1886, in the 

 Gray Herbarium (Ex. Paris Mus.), labeled .t.jamesoni Hook., but Hemsley* refers 

 that to J. spathulatum, while Moore places it under J. piloselloides Presl, which 

 Baker and Hemslcy both give as a synonym for spathulatum. Fournier 1 and Fee-', 

 however, retain Hooker's jamesoni, and the former cites Botirgeau's No. 3072. The 

 whole group which is composed of these small Acrostichums seems to have been 

 much confused or misunderstood, as is evidenced by the long list of synonyms in 

 Moore*s Index Filicum, 363, 364, under Elaphoglossnm. 



'The bibliography of this paper has been modified so as to conform to the usage 

 of this publication. Mr. Davenport has kindly consented, for the sake of uni- 

 formity, to the use of the name Dryopteris, although he himself still uses the name 

 Aspidium. 



-Biol. Centr. Am. 3: 689. 3 Mex. Crypt. 68. 'Acros. t. IS, jig. A. 



