42 ARKIV FÖR BOTANIK. BAND 1. 



truncate or cordate, the blade irregularly ovate and very 

 slightly incised or crenate, and the involucres few, very often 

 1 (or 2). Like Tr. pusillum, this species has a partially im- 

 mersed or winged involucre. 



The cells of a frond are pretty large, broad and open, 

 and partially regularly square. The walls are very thin, 

 scarcely 0,oo;5 mm, tig. 25, A, B. 



This species, as I have understood it, is of relatival}' 

 large size in comparison with the other minute South Ame- 

 rican forms or species of the same series. The length of fer- 

 tile fronds is 6 — 7 mm, but sterile and pinnatifid ones attain 

 a length of 8 — 9 mm and about 7 mm in width. 



It is distinguished from Tr. punctatum (fig. 31) hy thin, 

 tapering veinlets, which do not become thicker towards the 

 end, and by shorter and less numerous, deciduous hairs on 

 the margin. 



It is distinguished from Tr. pusillum Sw. (fig. 21) by its 

 broader, often rounded shape and, as already stated, by less 

 crowded venules, which are moreover connected in distinct, 

 repeatedly branched bunches; thej- also spread more from 

 each other and are more arcuate or flexuose, not straight, 

 erect and parallel. In Tr. sjjJioioides there are always many 

 veinlets, even among the lower and lateral ones, which tend 

 in a straight direction towards the margin, forming with this 

 a broad, sometimes almost a right angle. — These marks are 

 found again in the following species, ranking very near Tr. 

 sphenoides and forming with it a series, different from Tr. 

 jnisillnm Sw. When viewed together under the microscope, 

 these two species also look different, because sphenoides (and 

 its allies) is much more transparent than pusillum. 



There are several American species lately described, which 

 probably belong to tliis series, for instance Tr. setiferum (Bak. 

 ms.) Jenman, (Third supplement, Journ. of Bot. 1881, p. 52). 

 lahiatum Jenm. (Gard. Chron.. ser. 2, 24, p. 7), pinnatineria 

 Jenm. (Grard. Chron., ser. 2, 25, p. 787), fruticulosum Jenm. 

 (Gard. Chron., ser. 3, 15, p. 71). Fraseri Jenm. (Gard. Chron.. 

 ser. 3, 20, p. 266), Goeheliantim Giesenhagen (Die H^'meno- 

 phyllaceen, and Christ, Die Farnkräuter der Erde, fig. 41). 

 orhiculare Christ (Engler's Bot. Jahrbücher, 19. Beiblatt 47, 

 p. 26] only found sterile), and others. 



