78 Church . — The Polymorphy of 
at Naples follows the rule of the majority of its English 
associates and vegetates in shallow water from December 
to April, vanishing, like Dictyota in the Mediterranean, on 
the approach of summer. It is important to note that while 
Aglaozonia is also perennial in the Bay of Naples, Cutleria 
is the winter-form, completely disappearing by April, its 
existence being apparently terminated by a rise of temperature, 
instead of by a fall as on the English coasts. It is clear, 
therefore, that the vital capacities of the sexual plant 
towards temperature are much more limited than those 
of the asexual Aglaozonia , which is perennial, not only 
in the warmer waters of the Mediterranean summer, but in 
the cold waters of the North Atlantic and North Sea 
winter. 
If now we compare the geographical distribution of the 
known species of the Cutleriaceae l , we find that the order 
belongs naturally to the warmer seas. Thus, omitting the 
doubtful C. Laminaria , Kutz. of the Mediterranean, the group 
consists of two little known species, C. pacifica from Samoa, 
and C. compressa from La Guayra ; of C. adspersa of the 
Mediterranean district only 2 (Cadiz to Suez); of Zanar- 
dinia collaris , Mediterranean, West Indies, Polynesia, the 
Atlantic shores of Europe as far as Brest (Crouan). drifted 
specimens at Jersey (Harvey); and of C. multifida , also 
a Mediterranean and Atlantic type 3 . But this last, alone 
of the group, extends northwards to England, Shetland 
Islands, and the coast of Norway to Nordland (Kjellman) ; 
on the other hand, it is poorly represented in the North Sea 
district and absent in the Baltic. That is to say, the north- 
ward distribution of the sexual form appears to be limited 
1 De Toni, Sylloge Algarum, vol. iii. p. 300. 
2 Sauvageau (Journ. de Bot. 1897, p. 177) since gives C. adspersa and an 
undetermined Aglazonia, but neither C. multifida nor Zanardinia , as being 
abundant in winter, at low-tide mark, in the Gulf of Gascony ; and Mr. Batters 
informs me that C. adspersa is found at Brest. 
3 A doubtful Polynesian form of Aglaozonia described as Zonaria parvula var. 
duplex (Heydr. Beitr. Algenfl. v. Kais. Wilh. Land), placed by De Toni under 
C. multifida , might more possibly belong to C. pacifica . 
