Benedict: The genus Cekatoptekis 1<>7 



cells. Diels has recognized this relationship in Engler & Prantl's 

 Pflanzenfamilien, where Ceratopteris is ranked as a family (Parkeri- 

 aceae) coordinate with the Polypodiaceae, Gleicheniaceae, and 

 others in the group Eufilicinae. This seems to be a logical group- 

 ing but the indeterminate fructification is perhaps evidence of a less 

 highly organized development and, as has been suggested by Dr. 

 Underwood,* may be taken to indicate for this family a low posi- 

 tion in the order to which it belongs. 



The conclusions reached as to the classification of these plants 

 are based on an examination of the material in the Underwood 

 Fern Herbarium in the New York Botanical Garden, the Eaton 

 Herbarium at Yale University, and the National Herbarium, and in 

 the citation of specimens, these herbaria are indicated by the 

 letters U, E, and N. I wish to take this opportunity to thank 

 Professor Alexander W. Evans of Yale, and Mr. W. R. Maxon 

 of the National Museum, for the privilege of examining the ma- 

 terial in their care. 



The following forms seem to deserve recognition as species : 



Lamina of the mature sterile leaf usually oblong or narrowly deltoid, 

 pinnately divided ; spores 32. 



Annulus well developed, 20-70-celled, lip-cells present; seg- 

 ments of the sporophyl mostly more than 2 cm. long 1. C. thalictroides. 



Annulus few-celled, 4-10, lip-cells wanting; segments of the 



sporophyl mostly less than 1. 5 cm. long 2. C. Lockharli. 



Lamina of the sterile leaves broadly deltoid or pentagonal. 



Spores 32; the annulus few-celled, lip-cells wanting; mature 

 sterile leaves floating, the lamina pentagonal, not more than 

 20 cm. long, 2-4-pinnatifid 3. C. pteridoides. 



Spores 16; the annulus well developed, lip-cells present; mature 

 sterile leaves emergent, the lamina deltoid, 25-40 cm. long, 

 2-pinnate 4. C. deltoidea. 



i. Ceratopteris thalictroides (L.) Brongn. Bull. Sci. Soc. 

 Philom. 182 1 : 186./. 3, 4.. 182 1 



Acrostichum thalictroides L. Sp. PI. 1070. 1753- 

 Acrostichum siliquosum L. Sp. PI. 1070. 175 3- 



Leaves erect, 6-75 cm. long, the stipes 4-27 cm. long ; 

 lamina of the sterile leaf narrowly deltoid or oblong, 3.5-28 cm. 

 long, 2-13 cm. broad, 1-2-pinnate-pinnatifid, the pinnae ovate- 

 lanceolate or oblong, the segments linear-lanceolate to oblong or 



* Fernwort Papers, Linn. Fern Chapt. 17. 1900. 



