-„ HYDROIDA 



5^ 



calls our attention to the interesting fact that the polyps are basally attached to the psendohydrotheca 

 by a whorl of small chitinous bodies similar to that met with in Haleciidac, Plumulariidae , Lafoeidae, 

 and Campaiiulariidac ; they actnalh- attach the supporting lamella to the polj-p case. Systematically, 

 however, hardly any particular im]iortance can be attached to this character. The chitinous bodies 

 occur on the passage from the psendohydrotheca to the hard periderm of the stem. Also the periderm 

 of the stem has, in most species of Pcrigoiiiiiiiis a jellied cover, to which a lot of foreign bodies fasten 

 themselves so as to give the colony a foul appearance. 



The stinging cells in the tentacles of the Pcrigonimns-^^^ox^s show attempts at an arrange- 

 ment by belts. But it is not here so pronounced as in the Eudendriidae and the thecaphore hydroids. 

 This criterion, together with the psendohydrotheca, suggests that Perigoniiniis must be more nearly 

 related to the thecaphore hydroids than most other athecate hydroids. 



Perigonimus repens (Wright) AUman. 



1857 Eiidcudriiim rcpeiis, Wright, Observations on British Zoophytes, p. 84, pi. 82, fig. 8—9. 

 1864 Prrigoiiiiints — , Allman, On the Construction and Limitation of Genera among the Hy- 



droida, p. 365. 

 nee 191 1 — — , Broch, Fauna droebachiensis, p. 14. 



From the reptant stolons proceed thin polyp stems, up to 5 mm. long, more rarely dichotomi- 

 cally divided so as to bear two pol^-p.s. The polyps are about 0.5 mm. long, broadly fusiform, with 

 4—12 tentacles placed in a whorl, and surrounded below the tentacles by a thin jellied psendohydro- 

 theca, which is sometimes hardly observable. The pohp stems are wholly without rings, and all but 

 without wrinkles, and provided with a dark-coloured, but thin perisarc, which, on account of bottom 

 particles appendant, convey the impression of being granulous. 



The gonophores are dex'eloped into free medusae; when breaking away, they have two ten- 

 tacles and a well-developed, solid umbrella. The gonophores are borne individually on stems 0.2—0.3 

 mm. long, proceeding from the hydranth stems; on one hydranth stem is generally developed one 

 gonophore at a time, sometimes a couple of gonophores simultaneously. 



Material : 



The Faroe Islands, vSc'h'vaag. Depth 14—1672 fath. (on Nitciila intclriis). 



Certainly it is not this sjjccics that is delineated and described b)' the name of Pcn'goi/iiiins 

 repens in Fauna Droebachiensis (Broch igii). A comparison with the excellent drawings of the 

 species with Jilderholm (1909, Taf. I, Fig. 15 — 16), at once shows us the difference. The species 

 described and delineated from the Kristianiafjord has a stiff and robust structure; its perisarc is solid 

 and the colonies are open rhizocaulome formations; most probabh' the specimens in question should 

 have been referred to Perigonimus iiniscoides M. Sars. Perigoiiiimis repens^ on the other hand, has 

 thin closely set, irregularly curved polyp stems. Besides, the colonies from the Kristianiafjord bear on 

 the hydranth stems numerous gonophores without stalks, while the few gonophores of Perigoiiiimis 

 repens are borne on distinct small stalks covered with perisarc. 



