90 American Fern Journal 



noid; if the end of the sorus bends across the veinlet in 

 a crescent or horse-shoe shape it is said to be athyrioid; 

 if it grows across and down the other side of the veinlet, 

 or if two sori occur on opposite sides of the same vein, 

 it is a double or diplazioid sorus. 



The sorus in spleenworts is regularly attached to the 

 upper side of the vein, and if the vein is forked on the 

 upper branch, that is, nearest to the tip of the lobe on 

 which it grows. As Dr. Copeland expresses it, — " con- 

 fined to the acropetal side of the vein. "* Now when a 

 vein leads up to the angle between a lobe and the free 

 ^nd of the pinule or pinna, one side of the vein is acropetal 

 as regards the lobe and the other as regards the pinnule, 

 and quite logically a sorus often occurs on both sides. 

 If the pinule is strongly crenate or lobed, several vein- 

 lets on each pinule may be so situated as to have a sorus 

 on each side. But in this case the sorus on the side 

 toward the midvein of the lobe is likely to be shorter 

 than that toward the midvein of the pinule. (See figure 

 on page 81 of Vol. I of this Journal.) On the other 

 hand, if the veinlet is forked, as it usually is in A. filix- 

 Jemina, the two sori appear not diplazioid, but on differ- 

 ent branches and on opposite sides of them. 



Double sori may be found occasionally in other species 

 of Asplenium, as noted of A. pinnatifidum, by D. C. 

 Eaton. He says, "The sori are mostly single, though 

 here and there one will be diplazioid— most commonly 

 the lowest one on the superior side of the lobe. The 

 free edge is directed toward the middle of the lobe except- 

 ing the indusia of the sori nearest the midrib, and these 

 open toward the midrib, "f This is exactly the ease as 



just described for the Athyrium. 



♦Philippine Islands Bulletin No. 28: "The Polypodiaceae of the 

 Philippine Islands/' Edwin Bingham Copeland, p ge 76. 



t " Ferns of North America," D. C. Eaton, I. 63. 



