Some Northern Hydroid Zoophytes. 223 



lat. 56° 40' N, long. 169° 20' W., in 43 fathoms, that is, near the Aleutian 

 Islands in the North Pacific (Nutting) 1 ; and Kola Peninsula, 50 fathoms 

 (Jaderholm). 2 



Plumularia pinnata (Linn.). 



A cluster of weather-beaten but large colonies, dredged to the north of the 

 west part of the Dogger Bank — " below the nor'-west rough " — North Sea, 



Antenella secundaria (Linn.). 



A few of the simple hydroclades distinctive of this species occur' upon 

 the stems of Plumularia pinnata. The definite distribution of this species 

 in British waters is little known, owing to the fact that the earlier observers 

 considered it a variety of Plumularia catharina. 



From the north of the west part of the Dogger Bank, North Sea. 



Cladocarpus bonneviese, Jaderholm. 



A single complete colony of this rare species comes from the neighbour- 

 hood of Iceland. As the species has been found on only one occasion, when 

 it was trawled by the Norwegian North Atlantic Expedition to the west of 

 Bear Island, and as that specimen, although mature, appears to have been 

 fragmentary, a few details may be added to Miss Bonnevie's description. 3 



The colony consists of a polysiphonic main stem, 14 cm. high, rising erect 

 from an expanded basal piece, above which its thickness is T5 mm. The 

 lower 3*5 cm. of the stem is almost naked, but at that height a strong, 

 polysiphonic branch arises, and above that height stem and branch bear close- 

 set alternate hydroclades which spring from the anterior tube of the fascicle, 

 and lie in one plane. The majority of the hydroclades are simple, about 15 mm. 

 in length, but occasionally a pinna of the same length as a hydroclade springs 

 from the abcauline side of a proximal internode, and itself bears secondary 

 hydroclades, up to 5 mm. in length. These secondary hydroclades occur on 

 all but the three or four proximal internodes of the pinna. Internodal 

 septa occur: one, not prominent, at the base of the supracalycine sarcothecse, 

 another at the bulging lower half of the hydrotheca, and a third near the 

 base of the internode. Besides these a small septum generally runs across 

 the mesial sarcotheca. 



1 Nutting, "American Hydroids," pt. ii., Smithsonian Inst. Sp. Bull., 1904, p. 133, 

 pi. xl. fig. 8. 



2 Jaderholm, " Northern and Arctic Invertebrates in the Collection of the Swedish State 

 Museum," in Kungl. Svenska Vet.-Ak. Handl., Bd. 45, 1909, p. 103, taf xi. fig. 8. 



3 Bonnevie, Norwegian North Atlantic Expedition, " Hydroida," Christiania, 1899, 

 p. 94, as Aglaophenia compressa. 



