TRANSACTIONS OF SECTION K. 851 



2. On the Archesporium. By Professor F. O. Bower, F.R.S. 



Professor Bower pointed out that the recognition of the archesporium as con- 

 •sistently of hypoderiual origin cannot be upheld, and quoted as exceptions 

 Efjiiisetum, Isoetcg, Ophiof/lossum, and especially the leptosporangiate ferns. lie 

 ilaid down the general principle that the sporangia, as regards their development, 

 should be studied in the light of a knowledge of the apical meristems of the plants 

 in question. Where the apical meristems are stratified, the archesporium is hypo- 

 dermal in the usual sense ; where initial cells occur, the archesporium is derived by 

 periclinal divisions of superficial cells. Intermediate types of meristem show an 

 intermediate type of origin of the archesporium. He cited as an illustrative case 

 that of Ophioglossum, admitting that the hypodermal hand of potential arche- 

 sporium, which he had previously described, does not occur always or in all 

 species. But so far from thus giving up the case for a comparison with Lyco- 

 podium, he holds that as Ophiofflossum has a single initial cell in stem and root it 

 would be contrary to experience to expect or demand a hypodermal archesporium. 



3. Rote on the Occurrence in Neio Zealand of two forms ofPeJtoid ■ Trente- 

 pohliacea;, and their relation to the Lichen Strigula. £y A Vaughan 

 Jennings, F.L.S., F.G.S. 



The Trentepohliacea3 which form epiphyllous cell-plates are at present known 

 only from the tropics (with the exception of two imperfectly developed forms in 

 the northern temperate zone). They have been recorded from S. America (Bornet), 

 India and Oeylon (the Mijcoidea parasitica of Cunningham and Marshall 

 Ward), and the East Indies (Karsten), bat not up to the present time from New 

 Zealand. 



The present paper gives a summary of previous literature, and describes two 

 forms found by the writer in New Zealand. 



(1) Phycopeltis expansa (new species).— This species forms wide-spreading 

 yellow cell-plates on the leaves of Nesodaphne in the North Island (Rotorua), and 

 in the South Island (near Picton). Sporangia of two kinds : («) enlarcred cells of 

 the disc ; {h) borne singly on a hooked pedicel supported on a single°basal cell. 

 The plant is often associated with brown fungus byphse growino- between the cell- 

 rows, but not afl'ecting the growth of the alga. On the other hand, when attacked 

 by difi^rent hyphse, the result is the formation of the lichen Strigula, which in 

 Ceylon was shown by Ward to have for its algal element the Mycoidea parasitica, 

 Cunn. 



(2) Phycopeltis nigra (new species).— The second form is found also on leaves 

 of Nesodaphne with the Phycopeltis above described, and alone on fronds of 

 Aspleniumfalcatum. Sporangia in the disc are present, but no trace of sporancna 

 on pedicels is observed. "^ 



The plant always forms narrow, radiating, and branching bands, never circular 

 discs : the margins often irregular and tending to break into filaments. 



There are two distinct varieties : — (a) a comparatively large-celled form with 

 barren hairs well developed ; (6) a small-celled type entirely devoid of hairs. 



The most remarkable feature, however, is the colour. On the leaf the plant 

 appears perfectly black, and by transmitted light has the olive-green colour cha- 

 racteristic of many fungi, quite different from any of the ordinary Trentepohlias. 

 The plant is never attacked by fungus hyphre, and never takes any part in lichen 

 formation, even when on the same leaf with PhycojJeltis edpansa and the 

 associated Strigula. 



' Term used for those which form cell-plates (type Phycopeltis), as distinguished 

 from cell-filaments (Trentepohlia;. 



3 I 



