1;| -- 5 ] Setchell-Gardner: Melanophyceae 515 



17. Punctaria Grev. 



Fronds simple or more or less branched, monosiphonous, usually 

 complanate, membranaceous, linear to broadly expanded, attached by 

 a small discoid base, composed of several layers of cuboidal cells 

 similar in size or those of the surface layer much smaller ; reproduc- 

 tion by zoosporangia immersed in the tissue or slightly projecting or 

 bulging beyond the surface, and by gametangia usually partly or 

 wholly immersed in the tissue; both gametangia and zoosporangia 

 representing transformed surface cells, single or in small groups, 

 scattered promiscuously on both sides of the frond ; hairs present in 

 some species; paraphyses wanting. 



Greville, Alg. Brit., 1830, p. 52 and Syn., p. xlii. Diplostromium 

 Kuetzing, Phyc. Gen., 1843, p. 298. Phycolapathum Kuetzing, Phyc. 

 Gen., 1843, p. 299 (pro parte maxima). Desmotrichum Kuetzing, 

 Phyc. Germ., 1845, p. 244. Homoeostroma J. Agardh, Anal, alg., 

 Cont. Ill, 1896, p. 7. Nematophlaea J. Agardh, loc. cit., 1896, p. 12. 

 Rhadinocladia Schuh, Rhodora, vol. 2, 1900, p. 3, pi. 18. 



There can be little question as to the idea underlying Greville 's 

 proposal of the genus Punctaria, if we accept his P. latifolia as the 

 type. The specimen examined by Greville in its living state was 

 collected at Sidmouth on the south coast of England by Mrs. Griffiths. 

 It seems sufficiently certain that Wyatt's Algae Damnonienses, no. 9, 

 is practically a topotype, having been collected along the same coast 

 and not far removed from the actual type locality. Wyatt 's specimen 

 answers in every detail to Greville 's description and we base our idea 

 of the genus Punctaria and of the type species, Punctaria latifolia 

 Grev., on it. It is probably the same as the plant figured by Harvey 

 in Phycologia Britannica (plate 8). The Wyatt specimen is a 

 Punctaria also in the sense of J. G. Agardh (1896, p. 4, pi. 1, fig. 1), 

 although a distinct species from any included by him. The Punctaria 

 of Greville, besides including P. latifolia Grev. and P. plantaginea 

 (Roth) Grev., was also extended to include P. tenuissimum (Ag.) 

 Grev. This last species was removed later by Kuetzing to his Diplo- 

 stromium (1843, p. 298) and this genus, in turn, in spite of the refer- 

 ence to it as first or "type" species of Viva pi ant ag mi folia Lyngb., 

 is identical, partly in foundation and partly in content, with Kuetz- 

 ing's later genus Desmotrichum (1845, p. 244). Kuetzing's genus 

 Diplostromium has, then, the characters of Greville 's genus Punctaria. 



