— 27— 



there may be found a regular series up to the full developed form, 

 i ^ inches long, of which 3^-inch is petiole. There are in this 

 two or three approximate pairs of semi-lunate lobes, the lower of 

 which are alternate, and all decurrent. The lower lobes are 

 usually separated from the next pair by three times their diam- 

 eter, giving the frond a peculiarly attenuate appearance. The 

 upper pair of lobes is near the terminal lobe. This is emar- 

 ginate, as are those of the smaller plants, or it may bear in the 

 sinus a rudiment of a continuation in the form of a triangular 

 process, corresponding to the rachis and pair of lobes. 



In only one specimen have I seen a segment incised ; then 

 there was only one split on one of the lower lobes. There is no 

 midvein in the segment, but the main rachis sends out three or 

 four veins to each, which dichotomously fork twice, once near 

 the base and again near the margin. In small specimens the 

 fertile division is overtopped by the sterile, but in the larger 

 plants the sterile division reaches only the base of the fertile. 

 The latter vary in size from a short-stalked division bearing one 

 or two sporangia to a spike two inches in length. The spikes are 

 usually simple, but occasionally send out one or two short 

 branches near the base, and at times a group of 3-6 sporangia 

 grow on a small elevation of the main rachis. The sporangia 

 are sessile, or even sunk in the tissue of the rachis. After dehis- 

 cence one can look into the interior with a lens, and there is 

 nothing to obstruct the view but the outer wall of the back of the 

 rachis. The sporangia are set in groups, usually in pairs or fours, 

 with an interval of several times the diameter of the group be- 

 fore the next appears. Sometimes they are an inch apart. The 

 normal number of sporangia is five to eight, but large plants may 

 have as many as fifty. The spores are larger than any of sim- 

 plex I have seen, being 40-60 //. 



The color of the plant is at first a lively green, but rapidly 

 becomes yellowish, even before fructification; and after that 

 event are decidedly stramineous. They are rarely erect when 

 the plant is of considerable size, and are usually decumbent after 

 maturity. When dried under a moderate pressure the stems are 

 transparent. 



The vernation suggests lunaria. The fertile division is erect 

 or the top is a little in flexed. The sterile division grasps the 

 fertile at the sides, the segments are imbricated, and the terminal 

 segment is bent to cap the fertile. Often, as remarked, the sterile 



