34 DICTYOTA.CBLS. 



Next to the Fucacea this order is the most extensive 

 among Melanosperms, and the species are for the most part 

 objects of great beauty : some, like the singular Padina or 

 peacock's tail, almost without a parallel among sea-weeds. 

 None are of very large size, and none can be called mi- 

 croscopic. Those that are found between tide-marks gene- 

 rally grow in open pools, not far from high -water mark, where 

 they are exposed to the full play of sunshine for some hours 

 each day. The deep-water species generally frequent quiet, 

 sandy or muddy bays, or estuaries. Many kinds (like Aspe- 

 rococcus Turneri), which attain the length of but a few inches 

 when they grow between tide-marks, form fronds many feet 

 in length when growing in deep water. Some are nearly con- 

 fined to t'he southern shores (as Padina, Taonia,a.ndHaliseris). 

 Others are equally abundant in all parts of Britain. The 

 order is, however, chiefly characteristic of the warmer and 

 more sheltered parts of the sea. The species are very few in 

 high northern and southern latitudes, and gradually increase 

 from the fortieth parallel to the equator. Most of the genera 

 have a wide range, and many of the species are cosmopolites. 

 Padina Pavonia abounds throughout the tropics and along 

 the shores of Southern Europe, and reaches its northern limit 

 in the South of England. Here, however, it shows its sun- 

 loving propensities by growing in very shallow pools, the 

 temperature of which, during the recess of the tide, rises con- 

 siderably : and in warm summers its fronds are double the 

 size of those developed in cold seasons. Our Dictyota di- 

 chotoma is found from the shores of northern Europe to the 

 tropics; then at the Cape of Good Hope, the Antarctic 

 Lands, the western side of South America, and in New Zea- 

 land. The Asperococci have as wide a range. Haliseris 

 polypodioides extends from the tropics to lat. 54 on the West 

 of Ireland. Of the beautiful genus to which it belongs ten 

 species are known, all of them natives of tropical or subtro- 

 pical regions. Zonaria parvula is another straggler, belong- 

 ing to a genus all the rest of whose species are natives of 

 warm countries. 



None of the Dictyotea are used in the arts. 



