35 



hydrostatica, ifølge Sammenligning af ligestore Exemplarer 

 af begge, ved dets bredere, omvendt pæredannede Form, 

 idet dets nederste Del er stærkt buget, den øverste efter- 

 haanden smalere mod den but tilspidsede Ende; det lig- 

 ner saaledes mere Luftkammeret af Stephanomia insignis 

 Gegenbaur (1. c. Fig. 53), medens det hos P. hydrostatica 

 (Claus, Zeitschr. für wissensch. Zoologie 1860, Vol. 10, 

 Tab. 25, Fig. 1, 2; Keferstein & Ehlers zool. Beitr. Tab. 1, 

 Fig. 30) er betydeligt smalere eller næsten cylindriskt med 

 jevnt tilrundet øverste Ende. Det viser endvidere stærkt 

 markerede, regelmæssigt i lige Afstand fra hinanden fra 

 Spidsen til Basis løbende opak hvide Længdestriber, i An- 

 tal 9 hos det største Exemplar (hos det mindste kunde 

 de ikke tælles, da det hele Luftkammer ved Spiritusens 

 Indvirkning var bleven temmelig opakt), ligesom hos Ste- 

 phanospira, hvor deres Antal efter Gegenbaur er 8, og hvor 

 de kun forefindes i Luftkammerets nederste Halvdel. Disse 

 Striber, som ikke bemærkedes hos P. hydrostatica (de 

 skulle dog, efter Keferstein og Ehlers 1. c. Fig. 30, fore- 

 findes hos P. Philippii, Kölliker), ere egentlig verticale 

 mesenterieagtige Skillevægge, som forbinde den indre Sæk, 

 Luftsækken (Pneumatocysten) med Væggene af den ydre 

 Sæk eller Kammeret (Pneumatophoren), og saaledes holde 

 hin i dens Situs, ligesom det er paavist af Huxley hos 

 Agalma breve (Oceanic Hydrozoa Tab, 7, Fig. 2). " Luft- 

 kammerets Top har en stor cirkelrund purpur- eller brun- 

 rød Plet, hvis Pigment er mere sammenhobet eller mør- 

 kere i Midten end ved Peripherien ; hos det mindste Exem- 

 plar bemærkedes i Centrum af denne Plet et overmaade 

 lidet rundt pigmentfrit Sted. 



Stammens traaddannede Del (Svømmesøilens Axe, Köl- 

 liker), som bærer Svømmeklokkerne, er, ligesom den ne- 

 derste blæreformig udvidede Del, af en gjennemsigtig lys 

 carmosinrød Farve. Den er dog ikke ganske lige, men 

 svagt dreiet om sin Længdeaxe i nogle faa (2 — 3) Vendin- 

 ger. Borttager man Svømmeklokkerne, contraherer Stam- 

 men sig meget stærkt, og man bemærker da, at deres In- 

 sertionspunkter alle findes langs ad den ene Side af Stam- 

 men, paa hvilken de danne en Rad af sammentrykte til- 

 spidsede Flige, der sidde paa en skarp, ved Contractionen 

 mere eller mindre foldet eller kruset Længdekant (Fig. 2, 

 4, 23, k.), som i Stammens udstrakte, kun meget svagt 

 spiralt dreiede Tilstand (se Fig. 1) altid vender udadtil 

 og strækker sig nedad til den i Skivens Indsnit løbende 

 Længdefure, der ender nær ved Vegetationspunktet for 

 Vedhængene. 



Den nederste udvidede Del af Stammen endelig (af 

 Kölliker kaldet „Polypstokken", af Vogt „Skiven") har 

 Form af en ovenfra nedad noget sammentrykt Blære eller 

 en tyk, paa begge Sider, især den øvre, stærkt convex 

 Skive, hvis Dimensioner ovenfor ere angivne. Denne Del 

 er hos P. hydrostatica bleven opfattet paa en meget for- 

 skjellig Maade af to af de senere Iagttagere af Siphono- 

 phorer, Kölliker og Vogt. Den første antager den nemlig 

 for en særegen sækformig Udvidning af Stammen, den 

 sidste derimod for den i en næsten horizontal Bue dreiede, 



statica, when equally large specimens of both are compared, 

 by its wider inversely pear-shaped figure, the lower part 

 being strongly inflated, and the upper part gradually thinner 

 towards the obtusely-pointed extremity; it thus resembles 

 more the air-chamber of Stephanomia insignis Gegenbaur 

 (1. c, fig, 53), while in the P. hydrostatica (Claus, Zeitschr. 

 für wissensch. Zoologie, 1860, Vol. 10, Tab. 25, fig. 1, 2; 

 Keferstein & Ehlers zool. Beitr., Tab. 1, fig. 30) it is con- 

 siderably narrower and nearly cylindrical, with the superior 

 extremity evenly rounded. It further exhibits strongly 

 marked opaque white longitudinal stripes running regu- 

 larly at equal intervals from the apex to the base, in the 

 larger specimen, 9 in number (in the smaller they could not 

 be counted; the whole air-chamber having become rather 

 opaque under the influence of the spirit) as in the Ste- 

 phanospira, where their number according to Gegenbaur 

 is 8, and where they only occur in the lower half of the 

 air-chamber. These stripes, which are not observed in the 

 P. hydrostatica (they are said however, according to Ke- 

 ferstein and Ehlers 1. c, fig. 30, to be found in P. Philippii 

 Kölliker) are properly vertical mesenteric septa connecting 

 the interior bag, the air-bag (Pneumatocyst) with the walls 

 of the exterior bag or chamber (Pneumatophore) and thus 

 keep it in position, as has been shewn by Huxley in Agal- 

 ma breve (Oceanic Hydrozoa, Tab. 7, fig. 2). The top of 

 the air-chamber has a large circular purple-or brown-red 

 spot, the pigment of which is more accumulated or darker 

 in the centre that at the periphery. In the smaller speci- 

 men, an extremely small circular place free from pigment 

 was observed in the centre of this spot. 



The filiform part of the axis (axis of the swimming co- 

 lumn Kölliker) which bears the swimming bells is, like the 

 lower bladder-shaped enlarged part, of a transparent light 

 crimson-red color. It is not quite straight, but slightly 

 contorted in some few (2—3) coils. If the swimming bells 

 are removed, the axis contracts itself very strongly; and 

 the insertion points of the bells can then be observed all 

 along one side of the axis' on which they form a row of 

 compressed pointed lobes on a sharp longitudinal ridge 

 (fig. 2, 4, 23, k) more or less folded or corrugated by the 

 contraction. This ridge, when the axis is extended with 

 but a slight spiral twist, (see fig. 1) is always turned out- 

 wards, and extends downwards to the longitudinal furrow 

 (which runs in the incision of the disc) and ends near the 

 vegetation point for the various appendages, 



The lower enlarged part of the axis (called by Kölliker 

 "the polyparium", and by Vogt "the disc") has the form 

 of a bladder somewhat depressed, or of a thick disc strong- 

 ly convex on both sides especially on the upper side; and 

 its dimensions have been previously given. This part has 

 in the P. hydrostatica, been regarded very differently by 

 two of the recent observers of Siphonophores, Kölliker and 

 Vogt. The former considers it to be a peculiar sack-like 

 enlargement of the axis ; the latter on the contrary regards 

 it as a shortened flattened continuation of t^ie axis twisted 



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