Laing. — On the Algce of Neiv Zealand. 307 



Not much, however, is at present known about the in- 

 ternal distribution of our species. As the islands stretch 

 through ten degrees of latitude there is sufficient difference of 

 temperature to cause considerable differences in the marine 

 flora. Many of our species are principally or exclusively 

 northern in their distribution, others are only found in 

 the southern portion of the Islands. Of course, many plants 

 which are at present known from restricted habitats in New 

 Zealand will doubtless be found to be widely distributed. I 

 have already a considerable list of new localities, but I will 

 leave it for some future occasion, as I do not wish to burden 

 this paper with it, nor do I intend to discuss further the dis- 

 tribution of our species within New Zealand. 



There now remains to discuss the external distribution 

 of our Algas, which is of considerable interest It should 

 first be pointed out that no important order is wanting 

 in our list, though several of the smaller ones appear 

 to have no representative here. The small order, Squa- 

 mariece, which is found throughout the Atlantic, in the Indian 

 Ocean, at the West Indies and the Cape, and in Australia, 

 is probably the most considerable of these. Our genera, 

 too, as might be expected in such an ancient division of 

 plants, are, as a whole, very widely distributed. It is, of 

 course, to be expected that they should be most closely allied 

 to those of the corresponding latitude in Australia, and this is 

 the case. In south-eastern Australia there are about 180 

 genera, in New Zealand about 116. Of these, eighty-nine are 

 common to both districts. The warm Atlantic and the Cape 

 have eighty-five genera, and the Indian Ocean and the Cape 

 eighty-six genera in common (G. Murray, loc. cit.). Of 

 course, the percentages in each case show greater differences, 

 but it will be seen that the large proportion of genera com- 

 mon to New Zealand and south-eastern Australia is not 

 necessarily any proof of the close affinities of the floras. We 

 have, for example, more than fifty genera in common with a 

 district so remote and so different in climatical conditions as 

 the West Indies. On the other hand, there are only eight 

 genera confined to Australia and New Zealand — viz., Hormo- 

 sira, Xiphophora, Cystophora, Notheia — amongst the Fucacece ; 

 and four genera in the Bhodophycece, all belonging to the 

 order Sphcerococcoidece — viz., Curdicea, Melanthalia, Sarco- 

 cladia, and Dicranema — but, of these, Sarcocladia consists of 

 only two species — one belonging to Western Australia, and 

 the other, a New Zealand one, only very doubtfully placed in 

 the genus by Agardh. There is also a very doubtful species of 

 Dicranema from the Eed Sea. Such well-defined and dis- 

 tinctive genera as Hormosira, Xiphophora, Cystophora, and 

 Notheia, however, prove a distinct connection between our 



