1899] THE FAUNA OF THE SOUND 267 



been found off Greenland ; only 2 or 3 are southern, and 2 inter- 

 mediate. The northern character is even more manifest when one 

 includes all species recorded in literature as found in the Sound, many 

 of them, however, at its northern boundary. Fully half of the 48 are 

 northern, and only one purely southern. The Chaetopod faunas of the 

 Skagerack and Kattegat, on the other hand, contain more southern 

 elements, and especially a large number of species with west European 

 distribution — neither Arctic nor southern — a group that is but sparingly 

 represented in the Sound. 



The Bryozoa have not yet been thoroughly worked out ; but of the 

 9 species found, as well as those previously recorded, Merribranipora 

 membranacea is the only purely southern form ; the rest are either 

 northern or wide-ranging, but for the most part found in Arctic seas. 



The Echinoderma, of which there are 19 species, have a distinctly 

 northern character. The 3 holothurians are northern. Five starfish 

 are northern ; the sixth, Astcrias hispida, now first found in Swedish 

 waters, is a Shetland form. Of the sea-urchins, 1 is northern and 2 

 wide-ranging. The brittle-stars comprise 3 northern forms, 2 wide- 

 ranging, but tending more to the south, and 2 (alone among the 

 Echinoderms) purely southern. There are in the Kattegat 18 more 

 species of Echinoderma than in the Sound, and it is most suggestive 

 that of these 8 are southern, 7 intermediate, 1 wide-ranging, and only 

 2 northern. Obviously the Echinoderm-fauna of the Kattegat is far 

 more southern in its composition than is that of the Sound. So, too, 

 among the 29 species of Echinoderma, known from Helgoland, only 9 

 are northern, the rest being wide-ranging or southern forms. 



Only 16 species of Hydroidea have as yet been determined, but 

 these add Acaulis primariw and Cuspidclla grandis to the list of the 

 Swedish fauna, while Lovcnella producta and Opercular ella lacerata have 

 not before been found in Oresimd. This part of the fauna has a 

 northern character, more pronounced than that of Bohuslan, for 

 example, from which, though it lies farther north, many of the 

 northern species are absent. 



The list contains notes on other zoological groups, but nothing of 

 sufficient importance to be mentioned in this short abstract. The 

 foregoing account is based on Dr. Lonnberg's first and larger paper ; 

 the second paper adds only three or four species, among which may be 

 mentioned the new Hydroid, Clava glomerata (see Zoologischcr Anzeiger, 

 No. 578). 



As already observed, the chief factor in the distribution of species 

 within the Sound itself is the nature of the bottom. Dr. Lonnbera' 

 distinguishes the following regions and sub-regions : Shore-regions ; 

 Zostera-region ; Alga-region, with Laminarian, Furcellarian, and Coral- 

 line sub-regions ; deep-water, with bottom either of dead zostera, or 

 mixed, or sand, or clay. Of course each of these divisions merges into 

 those adjoining, but on the whole they may be characterised thus : — 



