l<)b Allgemeines. 



outer portions shrivel ; in the other species of Dicraea it falls away 

 altogether. Further leaves are formed on the floral shoots; these have 

 larger sheathing bases and smaller laminae, which soon shrivel away. 

 Inside these bracts is the flower, enclosed in a spathe like that of 

 Podostemon. The fruit differs from that of this genus in having equal lobes. 

 which both persist for some time. — D. clichotoma Tul., differs in having 

 the thin, ribbon-like thalli attached to the rocks for a great part of their 

 length, whilst in D. Wallichii Tul., the flattened thallus is considerably 

 thickened In this species the floriferous shoots are scattered over the 

 whole thallus. D. stylosa Wight, shows very considerable diversity 

 in the form of the thallus, for which reference must be made to the 

 original. 



The genus Griffithella resembles Dicraea in its vegetative parts, 

 which are however remarkably Polymorphie, the thallus often assuming 

 cup-shape, disc-shape, etc., the ordinary form of thallus resembles that 

 of Dicraea stylosa. The secondary shoots arise close to the apex 

 of the flat thallus and are rather more prostate than in Dicraea. Both 

 in this genus and in Griffithella the thallus grows in thickness by 

 tangential division of the cortical cells. Some or all the secondary shoots 

 finally become floriferous, whilst the tissues leading to them become 

 modified as in the genus last discussed. The dorsiventra! bilocular ovary 

 develops intö an anisolobous ribbed fruit with one deeiduous valve. 



In the earliest stages of Wiilisia seiagiuoides Wmg., as yet observed, 

 a clump of little floriferous shoots, surrounding two long shoots of quite 

 a different type, have been found. The latter may be as much as 50 cm. 

 in length, bearing long loriform leaves, and the author by analogy with 

 Hydrobryum regards them as representing the primary shoots of two 

 individual plants. Their anatomy is quite different from that of the 

 secondary shoots and resembles that of the primary axis of Hydrobryum. 

 At the base of the long shoot is a comparatively small, crustaeeous 

 thallus, bearing numerous closely crowded secondary shoots, which stand 

 stiffly erect. They are 2 — 7 cm. high, bear four rows of scaly leaves, 

 and are terminated by a solitary fruit. At the apex of still submerged 

 secondary shoots the scaly leaves bear long, deeiduous, green, assimilating 

 tips and it seems possible therefore that all the scales arise by the 

 enlargement of the bases of ordinary leaves and the loss of their tips, 

 as in Dicraea. The urceolate spathe is at right angles to the top pair 

 of the leaves, amongst which it is buried, and has two stiff teeth. Its 

 upper silieeous part ultimately falls away, exposing the anemophilous, 

 sessile flower, which is markedly dorsiventral. After dehiscence one 

 valve of the smooth fruit persists on the stalk. 



In the genus Hydrobryum the first stages resemble those in Dicraea 

 styloides. In H. lichenoides Kurz the primary axis remains short, whilst 

 in H. olivaceum (Gardn.) Tul. it may be as much as 5 cm. high and 3 mm. 

 thick with a large number of long leaves at its apex. In both cases two 

 outgrowths are formed at the base, the one a hapteron, the other 

 giving rise to the exogenously branched thallus, which in the mature 

 state is more or less flattened and firmly attached to the rock; it does 

 the chief work of assimilation. A secondary shoot is formed at each 

 branching of the thallus. The growing apex of the latter is like that of 

 Dicraea in most species, being provided with a collenchymatous root- 

 cap ; in H. olivaceum however the growth is marginal. In this latter 

 species the secondary shoots bear relativeiy long leaves, whilst in H. 

 lichenoides they are small. The frequently more or less prostrate axis of 

 these shoots, as in previous genera, does not appear above the surface 

 tili the time of flowering, when scales are developed on it as in Dicraea. 

 The terminal spathe is boat-shaped and splits along its upper margin, 

 allowing the anemophilous flower which is erect on a short stalk, to 

 tmerge. In H. lichenoides the form of the Stigmas is very variable. The 

 usually ribbed fruit (smooth and sessile in H. sessile Willis) is aniso- 

 lobous (almost isolobous in H. Griff ithii (Wall.) Tul.) with one 

 deeiduous valve 



