346 HYDROIDES NORVEGICA. 
the basal web, and none on the distal region of Salmacina incrustans, whereas those kindly 
sent by him presented from five to seven serrations on the basal web. 
MM. Caullery and Mesnil’ (1905) found a Haplosporidian parasite (Haplosporidium 
marchonie) in Salmacina Dystert from Cape Hague and Wimereux in great abundance in 
the coelom. 
Malaquin® (1909) mentions that round the gut is a vast sinus formed by the supra- 
intestinal. In Salmacina it lies between the coelomic epithelum and the intestinal epithelum. 
He thinks that this sinus represents the primitive blastoccel. 
Arnold Watson (in lit., 1916) found two opercula in a Filograna-like Serpulid—on 
opposite branchial filaments (each the central branch of the tuft). The new one resembled 
a shallow cup, and the old one was thrown off. 
Dr. Crossland finds Filograna common on the ships’ bottoms in the Red Sea, but, apart 
from this artificial habitat, he rarely sees it. Seamen invariably term it coral. 
Genus CLXXVIII.—HyproipsEs, Gunner, 1768. 
Cephalic collar separated posteriorly, and fused with the alar membrane. It trends to 
the ventral surface, where it forms a bifid median membrane. Branchiz of moderate length 
with short terminal processes. Dorsal filament on each side modified into a complete or a 
rudimentary operculum, the complete having two tiers, the upper a radiate vase-like appa- 
ratus of spiked horny rays, the lower a crenate vase of tough cutaneous tissue. Calcareous 
coiled tube, cylindrical, marked by lines of growth, and colonial. 
1. HypROIDES NoRVEGICA, Gunner, 1768. Plate CXVI, fig. 3—body; Plate CXXI, 
figs. 6—6c—body, tubes and opercula; Plate CX XX, figs. 9—9c—bristles and hooks ; 
Plate CXXXI, fig. 10—extremity of branchial filament; Plate CXXXIII, figs. 1 
and la—tubes and rudimentary operculum. 
Specific Characters.—Tube coiled, cylindrical, marked only by lines of growth ; often in 
masses. Cephalic collar separated posteriorly and fused with the alar membrane. The 
collar trends to the ventral surface, where it forms a bifid median membrane. Branchize 
fifteen to eighteen, variegated with pink ; filaments of moderate length, with short terminal 
processes ; pinnee of moderate length, slightly tapered distally. Dorsal filament on each 
side modified into a complete or rudimentary operculum of two tiers, the upper a beauti- 
fully radiate vase-like apparatus of spiked horny rays sixteen to twenty in number, the 
lower a crenate vase of twenty-five to twenty-seven divisions, the whole attached by a 
long stalk. The rudimentary organ has a short stalk and a clavate tip. Body of a reddish 
orange colour, with a pale alar membrane in front, rounded dorsally, slightly flattened ven- 
trally, and with a median groove from end to end, tapered posteriorly and ending in a bilobed 
anus. Anterior region of seven bristled segments, the first pair directed upward and forward 
' «Compt. rend. Soc. Biol.,’ t. lvin, p. 581. 
* © Assoc. Francaise,’ 1909, p. 135. 
