DUBLIN NATTTEAL HISTORY SOCIETY. 73 



the basal and middle lobes — the inner at the base on a level, and hori- 

 zontally forming nearly a straight series of three, with the inner eleva- 

 tion of each of the middle lobes. (Plate II., Fig. 2.) BasaVand middle 

 lobes mostly thrice dichotomons, the primary incisions deep, linear, about 

 one-half the depth of the lobes ; the secondary incisions linear, about one- 

 third the depth of the primary ; tertiary incisions shallow, triangular or 

 rounded, scarcely one -half the depth of the secondary; the ultimate 

 subdivisions bidentate. Sometimes the tertiary incisions are obscure or 

 obsolete, when the basal and middle lobes are therefore but twice dicho- 

 tomons, and the iiltimate subdivisions then mostly tridentate or quadri- 

 dentate. End lobe narrow, with nearly parallel sides at the base for nearly 

 half its length, thence suddenly widening, wholly included, acutely 

 emarginate at the end at the middle ; outer margin concave at each side 

 close to the notch, beyond which it is convex, its angles acute. (Figs. 1,2.) 

 In side view the frond rather more than three times longer than broad, 

 segments somewhat pjnramidal; in general outline inflated at the base, 

 side? concave immediately above ; again dilated about half-way up, the 

 central lateral projections directed upwards, with a sinus on each side 

 immediately above ; sides again contracted, and above again exhibiting 

 a lateral projection at each side ; end truncate, the upper edge (in empty 

 frond) showing the extremities of the various lobes and subdivisions. 

 (Fig. 3.) In end view the segment narrow -lanceolate, presenting at 

 each side, at the middle, the central, rouuded basal projections, and be- 

 yond it at each side, the pair of large conspicuous curved emarginate 

 divergent projections, the general outline presenting a doubly-hastate 

 appearance, the rounded projections iutervening, the upper edge (in 

 empty frond) showing the extremities of the various lobes and sub-di- 

 visions, the lobes presenting a somewhat ob-campanulate outline, with 

 a lateralminute projection at each side, its apex directed outwards. (Fig. 

 4.) In transverse view of a segment it is lanceolate, presenting much 

 the same outline as the end view, save that the outer edge being turned 

 away from the observer, the subdivisions of the lobes are not now ap- 

 parent, the foramen and basal projections being now uppermost, and in 

 this position very strikingly displayed. (Fig. 5.) Endochrome rich 

 green, sometimes not reaching to the margin of the frond, and thus leav- 

 ing a hyaline border, and containing numerous conspicuous rounded 

 scattered large granules. 



Plate 11. Fig. 1, front view. Fig. 2, same, empty frond. Fig. 3, 

 side view. Fig. 4, end view. Fig 5, transverse view, aU. magnified 200 

 diameters. 



This complex foiTQ is very pretty, but, without obtaining a side and 

 end view of an empty frond, is difficult to understand. Indeed, the outer 

 semicircular series, and inner series of three little apiculate elevations, 

 are not discernible when the frond contains its endochrome ; but the 

 large curved projections at the base of the segments, even in front view, 

 are readily seen, and under a low power, owing to the greater depth and 

 consequent greater opacity, appear like two darker portions at the base 

 of each segment; by focussing under a higher power, they are most easily 



