124 
THE SEAWEEDS 
a large number of species available along any local stretch of coastline, 
and which seem to exhibit a seemingly unlimited range of thallus forms, 
that it is not long before the morphologist is well out of his depth. It 
has already been emphasized that not too much reliance can be placed upon 
vegetative characters alone in making a species determination, a fact pro- 
foundly illustrated upon looking through the herbarium of some amateur 
collector. These seemingly almost identical thalli are found to be assigned 
to widely separated groups, often in quite different orders, while some 
species seem to be so sensitive to local environmental conditions that the 
range of forms exhibited by the species seems at first sight wide enough to 
accommodate several separate species. Size, texture of the frond and depth 
of colour can all be quite misleading and seem insufficient grounds for 
separating allied species. These pitfalls, of course, are not limited to the 
Reds alone, as numerous examples of such could be quoted at will from 
both the Greens and the Browns, but outstanding examples in the latter 
group are such genera as Hormosira and Ectocarpus, which are most dif- 
ficult to subdivide into a number of species although their generic characters 
are quite well marked. 
The text of this book follows the classification of De Toni in his Sylloge 
Algarum Omnium Hucusque Cognitarum (1889-1924), a classification essen- 
tially based upon morphological characteristics. It should be emphasized 
that such a classification is now obsolete and one which would not be 
retained except that the most natural classification, viz., that based upon the 
work of Prof. Harald Kylin of Lund, Sweden, is as yet rather incomplete, 
for although its orders and families are well established, there are still 
many genera among the Reds which have been incompletely investigated 
cytologically. Although their probable taxonomic position could be 
shrewdly guessed at, in the absence of reliable exact investigation they must 
remain unplaced. In the Appendices to this book there will be found an 
outline of the Kylin classification, and as many of the South Australian 
genera as we have been able to find placed are listed. Our information has 
been principally derived from the following works which use this classifica- 
tion :• — 
Tilden, J. E. (1935). — The Algae and Their Life Relations (Min- 
neapolis) . 
Taylor, AY. R. (1937). — Marine Algae of the North-Eastern Coast 
of North America (University of Michigan). 
Smith, G. M. (1938). — Cryptogamic Botany , Vol. I. (McGraw-Hill). 
Kylin, H. (1937). — Anatomic der Rhodophyceen (Berlin). 
Localities are given from which known specimens have been collected in 
South Australia, but in most cases the range could undoubtedly be extended 
by more widespread collecting. The term “Eastern Bays” includes Lace- 
pede, Guichen, Rivoli, and MacDonnell Bays. 
