Developmental Forms of Marine Algce. 
233 
specimen of N. reptans in the Herbarium of the British Museum, 
found on a stem of Laminaria Cloustoni, corresponds in appear¬ 
ance to some procumbent portions of N. ratnosum gathered from a 
similar habitat. 
As regards structure N. reptans is monostromatic and veined. 
N. ratnosum is also monostromatic in its upper, younger, and 
also in the procumbent portions. The cells of N. reptans 
measure 30 x 40/*, those of N. ratnosum are 35 x 50/x, but 
any difference in size may be accounted for by the difference in 
plane, age and habit. The shape is of much the same roundish oval 
type, Figs. 4, 5. 
F 10 . 4. Cells from thallus of N. ramosum f. reptans. x 62. Fig. 4a. 
Transverse section of thallus N. ramosum f. reptans from Crouan’s Flore de 
Finisterre, PI. 21, f. 140 bis. Fio. 5. Cells from thallus of N. ramosum. 
x 62. F 10 . 5a. Tranverse section of thallus of N. ramosum. x 62. 
The thallus of N. reptans is formed in rounded lobes, that of 
N. ramosum , though branched, also ultimately bears, rounded 
lobes. 
Crouan has described the cystocarps of N. reptans as spherical, 
placed towards the tips of the lobes 1 , Fig. 6. The position of the 
cystocarps in N. ramosum v. Smithii Batt. is similar*. In 
both cases, as has been described for N. reptans , they are “ sessile 
on the frond, hemispherical, composed of moniliform sporiferous 
filaments on a prominent basal placenta, and enclosed in a pericarp 
of very thin cells” 3 , Figs. 7, 8. 
The tetraspores of N. ramosum are borne along the upper margins 
of the frond, either in round or elongated patches, with a tendency to 
1 Crouan. 1851, loc. cit. Flore de Finisterre, p. 153. 
» ,, Flore de Finisterre, 152. 
5 Zanardini, loc. cit. 
