NO. 1867 AMERICAN FERNS— CHRISTENSEN 389 



in its more numerous veins, and in having the sori placed very near 

 to the margin. From D. Sprcngelii, which it resembles in pubes- 

 cence, size, and texture, it recedes by the absence of glanduliform 

 abortive pinnre and aerophore, by the position of the sori, by its 

 fewer veins, etc. Still, I think it best to place the species next to 

 D. Sprcngelii in the "system," mainly because its veins are closer 

 than in any species of the groups of D. opposita and D. pacJiyrachis. 



DRYOPTERIS MERCURII (A. Br.) Hieron. 



(Revision No. 66, Fig. 4,^) 



This is most probably a large, more hairy continental form of D. 

 Sprcngelii, in its typical form very characteristic, the pinnre 2-2.5 

 dm. long, thin, with numerous segments separated by open roundish 

 sinuses, the rachis and costse beneath furnished with long patent 

 hairs and the upper side more densely pubescent. But it will be, I 

 believe, impossible to draw a sharp line between the smaller forms 

 and the continental form of D. Sprcngelii mentioned above. Thus, 

 we have here a series of forms which grow larger from the Lesser 

 Antilles to Central America, the increase in size being associated 

 with an increase of pubescence, exactly as was the case in D. oppo- 

 sifa-D. pananioisis. Also, we find here the intermediate forms in 

 Jamaica. Provisionally, I find it best to let D. Mcrciirii, like D. 

 panamcnsis, stand as a species. 



Costa Rica : Santo Domingo de GoU'o Dulce. Tonduz IC023 (^Donucll 

 Smith 7215 B) ; I'ondus $885 (=£>. S. 7218). Haie a Turrialba, Pit- 

 tier 4oS7bis. Forets de Tsaki, Talamanca, 200 meters, Tonduz 9461. 



A critical form is W. A. Kellerman's no. 4864 from Puerto Bar- 

 rios, Guatemala ; in pubescence exactly D. Sprcngelii, in habit D. 

 Mcrcnrii. 



DRYOPTERIS THOMSONII (Jenman) C. Chr. 



(Revision 320, No. 67, as D. Stuebclii) 



Polypodium TJwnisonii Jenman, Bull. Bot. Dept. Jamaica II. 4: 130. 1897. 



Dryoptcris Thoinsonii C. Chr. Ind. Fil. 29S. 1905. 



Dryoptcris Stuebclii Hieron. Hcchvigia 46:340. pi. 6. f. /j. 1907. 



This species is given as unknown in my "Revision." In the U. S. 

 National Herbarium there are, besides a type specimen from Jen- 

 man, several specimens from Jamaica, and it is rather surprising 

 to find that the species is exactly identical with D. Stucbelii Hieron. 

 from Colombia. Thus we here come upon a new illustration of the 



