HYDROIDES NORVEGICA. 349 
1893. Hydroides lunulifera, idem. Ibid., vol. v, No. 11, p. 85. 
a 3 pectinata, idem. Ibid., vol. vy, No. 11, p. 85. 
» % norvegica, Marenzeller. Denks. Akad. Wiss. Wien, lx, p. 19, pl. iv, fig. 18. 
3 55 5 Levinsen. “ Hauchs” Togter, p. 354. 
1894. Pe guanerus = norvegica, Bidenkap. Christ. Vet.-Selsk. Forhandl., p. 138. 
1896. rf uncinata, Orlandi. Atti Soc. Ligust. Se. Nat., vol. vu, p. 158. 
Fh ip norvegica, Appellof. Berg. Mus. Aarb., xin, p. 12. 
1897. e $5 Michaelsen. Polych. deutsch. Meere., p. 186. 
1898. - a De St. Joseph. Ann. Se. nat., sér. v, p. 440, pl. xxiii, fig. 248. 
1904, a eS Journ. M. B. A., vol. vi, p. 232. 
1909. a 5 Fauvel. Bull. Inst. Oceanogr., exlu, p. 48. 
1910. . norvegicus, Southern. Proc. Roy. Irish Acad., vol. xxvin, p. 242. 
s a . Hlwes. Journ. M. B. A., vol. ix, p. 66. 
OSE 5 norvegica, Fauvel. Archiv Zool. Expér., vol. xlvi, p. 427. 
Fe - norvegicus, Ditlevsen. Danmark-Hksped. Groénl., Bd. v, p. 431. 
»  NSerpula reversa (Mont.), Riddell. Proc. Liverpool Biol. Assoc., vol. xxv, p. 65. 
1912. Hydroides norvegica, Crawshay. Journ. M. B. A., vol. ix, p. 347. 
iz ;; ss Wollebek. Skrift. Selsk. Krist., Bd. u, No. 18, p. 115, pl. xlin, figs. 1—6 ; 
yolk salting, takers Ike Jol, Uh, smiee, 
NOUS, Pg uneinatus, Ehlers. Deut. Sud.-Pol. Exped., p. 582. 
1914. ? Hwpomatus wncinatus, Treadwell. Univ. California, Zool., vol. xin, p. 225, 
»  Hydroides norvegica, Southern. Proc. Roy. Irish Acad., vol. xxxi, No. 47, p. 147. 
i rr é Fauvel. Campag. Scient. Monaco, xlvi, p. 324, pl. xxxi, fig. 25. 
1915. %5 55 Allen. Journ. M. B. A., vol. x, p. 644. 
» NSerpula vermicularis, Southern. Irish Sc. Invest., No. 3, p. 49. 
1917. Hydroides norvegica, Rioja. Anél. Poliq. Cantab., p. 80. 
Habitat.—Abundant in deep water all round the British shores attached to shells and 
stones as well as in the Laminarian zone. Under stones between tide-marks, Herm. On 
shells and laminarian roots, Lochmaddy (W. C. M.). 
Plymouth (Spence Bate and B. Rowe, Crawshay); Dublin Bay and West Coast 
of Ireland (Southern). Cosmopolitan. Persian Gulf (Gravier, Fauvel); Northern Seas 
(Wollebeek) ; Greenland (Ditlevsen). Is found in Sweden, Norway (fixed to Amphihelia 
prolifera, Kroyer) and Finmark (Malmgren) ; Mediterranean (Delle Chiaje, Grube, Philippi, 
Claparéde, Panceri, Marion); shores of France, De St. Joseph; Adriatic (Marenzeller) ; 
shores of Cantabria (Rioja). 
The prominent dorsal edges of the collar of Hydroides norvegica are supported by the 
first bristle-bundles, a considerable gap, however, occurring in the mid-dorsal line. It then 
passes ventrally to expand into a large thin lamella sloping on each side to a median notch, 
so as to be more or less bilobed, and is either reflected backward or stretched forward on the 
base of the branchie. 
The branchie (Plate CXVI, fig. 3) form two well-marked fans of fifteen to eighteen 
filaments, the dorsal filament in addition on each side being modified either into a complete 
or a rudimentary operculum, and it seems to be immaterial which side develops the complete 
organ, since it is sometimes the one and sometimes the other. The branchial filaments 
are of moderate length, and taper distally to end in a short subulate process, often concealed 
