HYDROIDA II 163 



Campanularia Johnstoni Alder. 

 1856 Campanularia johnstoni, Alder, A notice of some new genera and species, p. 359, pi. 13, fig. 8. 

 i860 Clylia bicophora, L,. Agassiz, Contributions to the natural history of the United States, Second 



Monogr. vol. 4, p. 304, pi. 29, figs. 6—9. 

 1868 — johnstoni, Hiucks, A History of the British Hydroid Zoophytes, p. 143, pi. 24, fig. 1. 



Creeping colonies, from the stolons of which proceed fairly long hydrotheca stalks, ringed at 

 the base and below the hydrotheca;, the middle part generally smooth. The stalk terminates below 

 the hydrotheca in a ball-shaped joint. The hydrothecse are of varying size, from twice to 2'/ 2 times 

 as long as broad, cylindrical or inversely conical, with gently curving basal part. The hydrotheca is 

 circular in section at the aperture; the opening margin is furnished with ten to sixteen sharp or point- 

 edly rounded, highly prominent teeth. The basal cavity is rather large, terminating at the top in a 

 narrow, sharply defined ring-shaped thickening of the inner wall, which in finely built specimens often 

 presents the appearance of a very low diaphragm. 



The gonothecae are attached to the stolons by a short, ringed stalk. They are cylindrical, 

 narrowing sharply at the base, cut off transversely at the distal end, and have deep transverse furrows 

 generally forming a slowly ascending, close spiral. The gonophores develope into free medusae (Clytia). 



Material : 



Iceland: Vestmano, depth 25 fathoms. 



The Faroe Islands: 6 miles N. by W. of Store Kalso, depth 60 fathoms 



deep hole at north point of Nolso, — 100 



61 ° 4 o' N, 7° 4 o' W, 135 



North Sea: 57°07' N., 2°4o' &, — 37 



Nutting (1915 p. 54) endeavours once more to divide Campanularia Johnstoni from Clytia 

 bicophora, partly on the ground that the latter species is said to possess a diaphragm, partly because 

 it is finer in the chitinose parts. The thinner chitinose formations involve, in Campanularia Johnstoni 

 as in other species, a more restricted thickening of the wall, so that there may often be some con- 

 siderable resemblance to a low diaphragm, and hydrothecee of this type always exhibit a marked ten- 

 dency to wrinkle up on preservation. There is, however, no reason to take all this as furnishing 

 sound specific characters, and we also find that all other investigators agree in uniting the two spe- 

 cies as Campanularia Johnstoni. This is doubtless correct. 



Campanularia Johnstoni is a widely distributed southern form, which thrives to a marked degree 

 upon Sargassum; it can, however, penetrate quite far down within the littoral region. In the northern 

 seas (fig. LXXXIV) it appears as a southern visitor, found once so far to the north as Hammerfest 

 on the coast of Norway, but otherwise only once met with at Bergen. In the North Sea it is more 

 common, as also at the Faroe Islands; it is of very frequent occurrence round the British Isles, but 

 rare in Iceland waters. Its distribution is that of a species typically belonging to the warm atlan- 

 tic current. 



