36 ARKIV FÖR BOTANIK. BAND 1. 



The cellular structure of Tr. pusillum is regularly reti- 

 culated, owing to the very crowded parallel venules, Kke Tr. 

 reptans, but in this case the walls are much thinner than in 

 all the preceding plants, being only 0,oo2 — 0,oo3 mm thick; 

 tig. 20, B, C, 21, B, 0. 



The involucre is distinctly winged by the apex of a lobe, 

 and thus more or less sunk in the frond, although in old sam- 

 ples it may appear free through the bursting of the fragile 

 wing. (Swartz therefore says in his original description: 

 «urceoli exserti^), Syn. Fil., 1806, p. 142). The involucral lips 

 seem to be a little larger than in Tr. S])henoides and its allies 

 (s. below). — 



The true Tr. pusillum Herb. Swartz, which is a very 

 peculiar species of Didymoglossum, is probably not known 

 with certainty to live in any other countries than the West 

 Indies, Jamaica, Swartz. Nevertheless I suppose, that Fee's 

 Didymoglossum angtistifrons, Fil. Antill., t. 28, f. 5, belongs 

 here, but I am not sure. 



8. Tricliomanes sphenoldes Kunze. — Fig. 22—25, 

 28 C. 



G. Kunze, Linuaea IX, 1834, p. 102; Die Farrnkräuter, 1840 — 47, 

 T. 88, Fig. 2, p. 215. 



Syn.: Sloane, A Voyage, t. 27, fig. 1 (pars speciminis)? 

 » Didymoglossum sphenoides Presl et JJidymogl. Hookeii 



Presl, Hymenophyllaceae, 1843, p. 23. 

 » Tricliomanes sphenoides, Flora Brasil., f. 23, 1859, p. 277. 

 » » reptans Hook, et Grev., Ic. Fil. 1829, t. 32 



» » and Hook, and Bak., Syn. Fil., ed. 2, 



1883, p. 74 (nen Swartz). 

 » Hemiplilehium punctatum Poir., Prantl, Die Hyraeno- 

 phyllaceeu, 1875, quoad Taf. II, Fig. 18. 



I have had the opportunity in the Herb. Stockholm of 

 examining several forms of Didymoglossum, which all come 

 very near to the preceding (Tr. pusillum), with respect to 

 the combined marks of very small size, few and short lobes 

 or almost entire fronds, and very fine and numerous venules, 

 tilling the whole area of the frond. They belong to that 

 little group, which in Hook, and Bak. Synopsis, ed. 2, p. 74, 

 is represented by the two species punctatum Poir. and sphc- 



