io6 



HYDROIDA II 



Sertidardla fusiformis assumes a highh- characteristic appearance from the peciiHarity that it 

 has often on stem or branches two or three short branchlets proceeding simultaneously from the same 

 point, these short branchlets consisting of a single internodium, or more rarely a couple, with large 

 hydrothecEe almost terminally placed. An excellent picture of this is given by Jaderholm (1909 Taf. 

 II, fig. 9). His specimens undoubtedly belong to ScrtularcUa ftisiforniis, and are only remarkable in 

 having the internodia entirely smooth; here, however, all transition stages occur, so that we are not 

 warranted in setting aside the specimens on such ground as types of a distinct species. 



Sfrtiilarrlla fusiforiuis is probably a warm atlantic species, but its occurrence is little known. 

 In the waters investigated, it is previously known from the Hebrides, and from the Clyde Sea area; 

 to these, Jaderholm adds a single find from Spitzbergeu, and the species has now also been taken 

 bv the "Ingolf" about midwav between the Faroe Islands anS Iceland. 



Sertularella rugosa (Linne) Hi neks. 

 1758 Scrtiilaria rugosa, Linne. Systema natura:, Ed. 10, p. 809. 

 1868 Sertularella rugosa, Hincks, A History of the British Hydroid Zoophytes, p. 241, pi 47, fig. 2. 



Upright, irregularly branched small colonies without pronounced main stem; the latter is mono- 

 siphonic. The colony is divided b\' oblique nodes into short internodia, each bearing a Indrotheca 

 directed alternately to either side, and situate on the upper half of the internodium. The hydrothecEe 

 are broad oval or barrel-shaped, with deep trans\-erse furrows, which are particularly marked on the 

 abcanline side, where a very deep furrow is alwa^'s found inunediately beneath the aperture. The 

 opening forms an angle with the hydrotheca axis, and is turned awa\' from the branch; it is furnished 

 with four low, often somewhat indistinct teeth, between which four triangular lid plates are attached. 

 The polyp has a large abcauline blind sack. 



The gonothecse proceed from the internodia close under the hydrothecae. 

 They are egg-shaped or more oval, with deep transverse furrows, and have distally 

 a central broad opening, surrounded by four short strong teeth. 



Alaterial: 



Jan .Ma\en, depth 15 fathoms (East Greenland expedition). 

 Iceland: (irindavik (depth not stated) 



10 miles W. of Akranes, on algae 

 Stykkisholm, depth 30 fathoms 

 Bredebngt (without further details) 

 The Faroe Islands: Sohnunde, on algae 



Thorshavn, on algte, depth 3 — 4 fathoms. 

 VestmanhaxMi, — 3i5 — 4 ~ 



The available illustrations of Scrtularrlla rugosa are \'er>- little characteristic, and this applies 

 especially to Nutting's (1904 pi. 17, fig.s. i — 5) which present an entirely misleading impression, in- 

 asmuch as they suggest that the hxdrothecae are distinctly ringed. A new drawing is therefore given 

 here (fig. LVII) showing the deep transverse furrows; particularly characteristic is the deep abcauline 

 furrow beneatli the aperture. 



Fig. LVII. Hydrothecie. 



of Sertularella rngoso 

 from Herlo near Bergen 



(X 40). 



