6 7 



forms of Nitella and Chara, but is more compact. The mature glomeruli of Tydemania are 

 contiguous, are about i cm. high and i — 2 cm. broad and arise each at the temporary apex 

 of the growing branch axis, which divides into four equal ascending branchlets (fig. 154, upper 

 node) ; these branchlets, each dividing by repeated divaricate dichotomies in alternate planes 

 and at short intervals (fig. 153 a), combine to produce a globular tangle of laxly interwoven 

 ramuli, which measure 240 u. at base close to the branch-axis and taper to 63 u. at the apices. 

 Subsequently the branch-axis résumés its growth and from a new node 1 cm. higher up produces 

 a fresh glomerulus; and thus a series of six or more glomeruli is formed. This interrupted mode 

 of growth recalls distantly that of Halimeda. But the likeness goes no further than the fact of 

 growth by interrupted stages. For in Tydemania the growing axis is a single monosiphonous 

 filament, whereas in Halimeda there is an axial strand composed of several parallel filaments 

 which at the resting apex of the joint (internode) fuse in special manners characteristic of the 

 various species, preparatory to the formation of a new joint (internode) (confer Journal of 

 Botany XLII. 1904, p. 193). 



The geographical distribution of T. expeditionis is confined to the Malay Archipelago. 



2. Tydemania Gar diner i n. sp. 



Syn. Tydemania expeditionis A. & E. S. Gepp in Trans. Linn. Soc. (Bot.) VII. 1908. p. 174, pro 

 parte, pi. 23, figs. 18, 19; and op. cit. (Zool.) vol. XII. 1909. p. 384, pro parte, pi. 48., 

 figs. 18, 19. 



Hab. INDIC. Chagos Archipelago, Salomon, on reefs exposed at lowest tide, J. Stanley Gardinerl, 

 and Amirante, 44 — 20 fathoms, J. Stanley Gardinerl i Sealark" Expedition, 1905. 



Plants low, laxly caespitose, calcified. Main axis prostrate, monosiphonous, cylindric, 

 250 — 400 ij. thick, now and again emitting branches, some which are cylindric and bear rhizoids 

 (which are tough and adhere closely to the substratum), and others which are moniliform and 

 divide trichotomously and then dichotomously 5 — 6 times, divaricately, at short intervals and 

 in alternate planes, and bear ultimately the flabella on 4 — 6-beaded stipites (250 a in diam.) ; 

 the flabella are monostromatic and composed of laterally connate, dichotomously branched 

 filaments, 50 u. in diam. (rarely 40^.) above, 200 a at base, where the articuli are very short. 

 Glomeruli absent. [Fig. 155]. 



When treating of this plant two years ago (in Trans. Linn. Soc. loc. cit.) we were 

 inclined to regard it as a well-developed example of the flabellate form of T. expeditionis ; 

 upon further consideration however we are convinced that it is a proper species, and we have 

 much pleasure in naming it after its collector, Prof. J. Stanley Gardiner. It differs from 

 T. expeditionis in habit, in details of ramification, and in geographical distribution. It forms a 

 low laxly caespitose patch 4 — 7 cm. wide, consisting of hundreds of small calcified flabella 

 about 1 cm. high, springing from one or more prostrate branched main axes, which are firmlv 

 attached here and there by rhizoids to the substratum. It shows no tracé of glomeruliferous 

 shoots, such as predominate in and are characteristic of T. expeditionis. Further, whereas in 

 T. expeditionis the flabella are few and borne on very short simple stalks which spring singly 



