C2 HYDROIDA 



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

 by a whorl of small chitinous bodies similar to that met with in Halt-ciidac, Plitiinilnriidac, Lafoeidac^ 

 and CanipcDuilariidac ; they actually attach the supporting lamella to the polyp case. Systematically, 

 however, hardly any particular iiuj^ortance can be attached to this character. The chitinous bodies 

 occur ou the passage from the pseudohydrotheca to the hard periderm of the stem. Also the periderm 

 of the stem has, in most species of Perigonimus 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 /'cV7^(','//;/.'«j-species show atteiupts at an arrange- 

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

 This criterion, together with the pseudohydrotheca, suggests that Pcrigoiiiiiiiis must be more nearly 

 related to the thecaphore h}droids than most other athecate hydroids. 



Perigonimus repens (Wright) Allman. 



1S57 Eudcndrmm repois^ Wright, Observations on British Zoophytes, p. 84, pi. 82, fig. 8 — 9. 

 1864 Pfrigonimtis — , Allman, On the Construction and lyimitation of Genera among the Hy- 



droida, p. 365. 

 nee igii — — , Broch, Fauna droeljachiensis, p. 14. 



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

 cally divided so as to bear two polyps. 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 pseudohydro- 

 theca, which is sometimes hardly observable. The polyp stems are wholh- 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 graniilous. 



The gonophores are developed 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 h3'dranth stem is generally developed one 

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



Material : 



The Faroe Islands, vSorvaag. Depth 14—1672 fath. (on Nncula iniclrus]. 



Certainly it is not this species that is delineated and described by the name of Perigoiiimns 

 rcpcns in Fauna Droebachiensis (Broch 191 1). A comparison with the excellent drawings of the 

 species with Jaderholm (1909, Taf. I, Fig. 15 — 16), at once shows us the difference. Tlie 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 probably the specimens in question should 

 have been referred to Perigonivnis niuscoides M. Sars. Pcrigonin/iis irpnis, 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 Perigonivnis 

 repens are borne on distinct small stalks covered with perisarc. 



