82 



in a locality where these grow or have grown. That they are 

 mutations seems very doubtful, because the actual differences are 

 so great, and especially since in these differences they resemble 

 the other reputed parent. For example, sterile intermediates are 

 known between Dryopteris viargiiialis and six other species. 

 Some resemble mavginalis most, some the other species, but all 

 agree in possessing distinctive characters of each of two species. 

 For similar reasons, these forms cannot be satisfactorily explained 

 on ecological grounds. 



If it is objected that fern hybrids must, because of the condi- 

 tions required for the transference of spermatozoids, be too rare 

 to account for these plants, which are rather common, it may be 

 said that Dryopteris cristata x inarginalis, one of the authenticated 

 crosses, is perhaps the commonest of them all. It may be ex- 

 pected in any swampy woodland where the parent specie! occur. 

 This being the case, we are bound to expect the other forms to 

 be found at least occasionally, and it seems only logical to con- 

 clude that such intermediate sterile forms as are analogous in 

 general characters to D. cristata x marginalis belong in the same 

 category and are likewise hybrids. 



In the region in which the writer has studied these plants, 

 Dryopteris is represented by six specific units which seem to 

 hybridize more or less readily, representing a total of fifteen pos- 

 sible combinations of two species. Of these fifteen, two are 

 already described. Of the remaining, probably eleven have been 

 found, and descriptions for most of these are in preparation, some 

 by Miss Slosson, some by Dr. Philip Dowell, and some by the 

 writer. 



Both papers were discussed at length, and the Club adjourned 

 at 5:45 o'clock. C. Stuart Gager, 



Secretary. 

 March 10, 1908 



The meeting was called to order at the American Museum of 

 Natural History at 8:30 p. m. by the Chairman of the program 

 committee. There were twenty-five persons present. In the 

 absence of all officers of the Club, no business was transacted. 

 The scientific program consisted of an illustrated lecture entitled 



