I16 
as part of the reproductive processes of the A/hnfeltia 
or as entirely separate plants parasitic on the Ahnfeltia 
thallus. Recently the convergence of three research 
workers to the view that the emergences are integral 
parts of the Ahnfeliita and concerned with its reproduction, 
disposes of the ‘“‘ genus’”’ Stervocolax. As it has gained 
such a place in the literature the name is retained in this 
list without prejudice to the results of investigation as 
published by Rosenvinge (“‘ Det. Kgl. Danske Videns- 
kabernes Selskab, X2’’), B. D. Gregory (“Annals of Botany’ 
44, 1930), and E. Chemon, “ Bull. de la Soc) beat-sde 
France,” 77. 
16. Chondnia tenwussima. 
This plant is easily confused with Rhodomela subfusce 
by the inexperienced. The two plants may be dis- 
tinguished from one another by their anatomical structure, 
An illustration of the organisation of the Chondnia 
thallus will be found in “ Oltmanns,” Vol. II, p. 318, 
fig. 3. 
17. Khodomela subfusca. 
An illustration of the anatomical features of this plant 
will be found in “‘ Oltmanns,”’ Vol. II, p. 310, figs. 6 and 7. 
18. Callithamnion Hookeri and C. polyspermum. 
Callithamnion species are not easy of identification by 
the beginner. Some species, as for example, C. arbuscula 
or C. tetvagonum, are readily recognisable; others are 
more nearly alike in habit and are distinguishable only by 
minute differences of proportion or of habit of branching. 
Some species such as C. Hookert and C. polyspermum shew 
grades of variation of stature and in method of branching 
within fairly wide limits, with the result that inter-grade 
forms between the types exist side by side (Fig. 67, Plate 
XVII; figs. 69, 70, Plate XVIII) and make exact deter- 
mination difficult. | 
