Pterocladia lucida in New Zealand. The P. lucida group is ‘distinguished by large size, ancipitous T.S. of all parts, with rhizines scattered or thickly clustered throughout the medulla but always more densely developed and straighter in the inner cortex (Pl. 45, Figs. 9 and 10); there is usually a strong midrib in older axes; the carpostomes are slightly sunken, never raised on a projection, faintly rimmed, and usually multiple in each cystocarp with no regular arrangement; tetrasporangia often show a V-arrangement near the retuse apex of the growing sorus. The complex holdfast, described and figured by Moore (1944) seems to be a very stable character, contrasting strongly with the very simple attachment organs of P. capillacea. The material examined exhibiting these common features falls into several sets, linked by intermediates, and all obviously much more closely related to one another than any of them is to P. capillacea or to the Australian P. pectinata. Harvey (1863), in discussing the variability of P. lucida, suggests the possibility of difference between Australian and New Zealand specimens, but the few Australian plants available here show a range of forms similar to ours, though sections were inconclusive. The point can be decided only when more information is available about the genus in Australia. Mrs. Valerie May Jones, of the Fisheries Section of the Australian Council of Scientific and Industrial Research, mentions in a letter (5th May, 1944) a specimen in the Sydney Herbarium called P. pectinata from East Cape, New Zealand. The present writer has made collections from within a few miles of East Cape, on either side, and has met with nothing to correspond either with the Lucas P. pectinata specimen in the Laing Herbarium, or with Mrs. Jones's brief description of the New Zealand specimen in the Sydney Herbarium. Agardh (1876, p. 545) proposed two rather, ill-defined varieties, α and β, of P. lucida, but did not quote specimens or localities for either. He had probably by this time seen Berggren's specimens collected in New Zealand in 1874–75, amongst the fragments of which that have returned to New Zealand herbaria there are several forms represented, but it is not easy to relate the varietal diagnoses to these. Laing (1939) says “apparently common in at least two forms.” Their status is of economic importance in that they behave rather differently in agar processing. It would be interesting to see to what extent such differences depend on proportion of rhizine to cellular tissue, a ratio which varies from part to part of one plant but is apparently higher in the more robust forms. Two difficulties arise—(1) that of defining sharp limits between forms, and (2) that of deciding to which the name lucida1 really belongs if there are two or more species involved. The only feasible course seems to be to illustrate the chief New Zealand forms (this has not hitherto been done for P. lucida in any part of its range) and to distinguish, as a matter of convenience, those kinds which, though of uncertain status, have some practical significance.