4. 

 of tlie leu.::, r.Iit^ped like tlie half o'' ■■'ou'Me ^orvex lens, 

 arcT vritli itn edrec directe'' respectively toward the haee 

 and apex of tlie stem. 



Htmstein ('nO) h.as already si own tliat th.e leaf of M*\r- 

 siliii lias a two sided apical cell, and he fij-^urec it (pi. XIII 

 15. 1"^) as havin/- approximately the position riven above, 

 "but he did not deGcribo the ori^^in of the apical cell except 

 in the leaves of the very young embryo. Th.is arrees in oririn 

 sliape and position v/ith. tlie apical cell of the leaf as 

 foimd in most of the otlier Leptosporangiate Ferns that h.ave 

 been studied. They have been tims described by Hofneister 

 (•62) in Aspidiiim, by Strasbm-ger ('73) and Campbell ('93) 

 in Azolla, by I\ny ('75) in Ceratopteris, by Klein ('87) in 

 Polynodinn, by Bower ('89) in Trichomanes, pjid by Campbell 

 (*87) in Onoclea. In Pteris h.owever, while th.e origin and 

 shape of the a.plcal cell are tlie si^me, its position, as 

 sho"m by Hofmeistor ('62) tmd Klein ('84) is exactly at 

 rijO-ht angles to that found in the other genera mentioned. 

 That is the edges are directed transversely to tlie stem 

 and segments are cut off toward and away from tlie stem, apex 

 altornr'.tely. 



In Pilularia, tlie only other -^enus of the I'larsiliaceac, 

 Bower ('89) and Menuier ('87) describe the apical cell of 

 the leaf as two sided, while Campbell ('93^pl42. '95 p.413) 

 states tliat it is tetraliedral, and differs tlius fro:^ ih.at o 



