30 



Denne nye Art afviger i mange Eetningor fra alle 

 tidligere kjendte Arter, og den niaa ubetinget indtage en 

 Grænsestilling inden Slægten Tubiilaria, hvis den over- 

 iiovedet skal indordnes nnder nogen tidligere kjendt Genus. 

 Da dens Gonosome kun er meget utilstrækkelig kjendt, anser 

 jeg det dog ikke for rimeligt her at give den nogen Sær- 

 stilling. Den chitinose Perisarc og dens traadforinige Ten- 

 takler, stillet i to Kredse, fører den ind under Slægten 

 Tuhtlaria, medens dens solitære Optræden og dens Mangel 

 paa Hydrorhiza tyder paa Slægtskab med CoryniorpJia, og 

 denne Art danner snaledes, sammen med T. iwolifer — 

 oftest solitær Optræden, og Meduse med en Tentakel — 

 Overgangsformer mellem de to nævnte Slægter. 



Hydrocaulus har øverst en Diameter af ca. o mm., 

 og den smalner jevnt af nedover indtil den nederst lober 

 ud i en ganske fin Spids, hvormed den paa de to af mig 

 undersøgte Exemplarer var fæstet til et haardt Underlag 

 (en Sten og Stykke af et Serpularør). Samtidig med denne 

 Afsmalnen bugter Hydrocaulus sig sterkt, saa at den i hele 

 sin Bygning minder i)aafaldende om et Horn. Perisarcen 

 er sterkt gulfarvet og aldeles blank. Eiendommelig er og- 

 saa den store Krave, som danner Perisarcens Alslutning 

 opad, og fra hvis Bund den ubedækkede Coenosarc 

 stiger op. 



Hydranthen er skarpt adskilt tra Stilken, og dens 

 Bygning afviger fi'a det almindelige Forhold hos Tubulari- 

 derne, idet dens Diameter, som er ganske liden mellem de 

 proximale Tentakler, tiltager mod den distale Ende, saa 

 at den ved Mundaabningen naar op til 8 — 10 mm. Ten- 

 taklernes Bygning og Anordning stemmer overens med de 

 øvrige Arters. 



Blastostylerne er deriraod hos denne Art omdannet 

 paa en Maade, der saavidt mig bekjendt, ikke har Side- 

 stykke hos nogen anden Hydroide. Jeg har kun havt An- 

 ning til at undersøge dem paa et tidligt Stadium af deres 

 Udvikling, og det er meget muligt, at deres Form i ud- 

 voxet Tilstand ikke vil stemme med min Beskrivelse af 

 dem; men de afviger i sit Anlæg saameget fra Blastosty- 

 lerne hos de øvrige Tubularider, at de neppe nogensinde 

 vil miste sin Eiendommelighed. Blastostylernes Kreds om- 

 kring Hydranthen er saa tæt, at de synes at danne en 

 kompakt Ring om den, med en nogenlunde jevn Overtlade. 

 Ved at undersøge de enkelte Blastostylers Bygning ser 

 man, at de dannes af en meget kort Stilk, der i sin distale 

 Ende er skjærmformig forgrenet, og at hver af de 4 — 5 

 Grene strax breder sig ud til et kugleformigt eller ovalt 

 Legeme, hvis Overflade overalt nndtagen lige ved Stilken, 

 er besat med smaa runde Forhøininger. Jeg har ved Snit- 

 serier undersogt Bygningen af disse eiendommelige Dan- 

 nelser, og det viser sig, at hver af disse Smaagrene, der 

 udgik skjærmformig fra Moderstilken, meget snart selv 

 danner en Skjærm bestaaende af en Mængde fine Forgre- 

 ninger, der udgaar fra omtrent samme Punkt At man 

 ikke kan se denne anden Forgrening kommer af, at Ekto- 

 dermen fortykkes mellem Grenene og ganske udfylder 

 Rummet mellem dem. Gonoforerne anlægges i den distale 

 Ende af alle disse tine Grene,, og man ser dem udvendig 



This new species difters in many ways from all pre- 

 viously known species, and must certainly occupy a border 

 position within the genus Tulntlaria, if it is to be classed 

 under hitherto known genus. As its gonosome however. 

 is only very imperfectly known, I do not consider it would 

 be right to give it any peculiar position. Its chitinous 

 perisarc, and its tiliform tentacles, standing in two circles,. 

 entitle it to a place in the genus Tiihulnr/a, while its soli- 

 tary occurrence and absence of hydrorhiza indicate an af- 

 finity with Cori/iiiorplia, so that this species, together with 

 T. p"olijer — generally of solitary occurrence, and having 

 a medusa with øne tentacle — are transition forms be- 

 tween the two above-named genera. 



In its upper part. the hydrocaulus has a diameter of 

 about 5 mm., and tapers gradnally downwards until it 

 ends at the Ijottom in quite a tine point, with whieh. in 

 the two specimens examined by me, it was attached to a 

 hard substratum (a stone and pieces of a Serpula tube). 

 Simultaneously with this tapering, the hydrocaulus curves- 

 sharply, and thus acquires a striking resemblance to a horn. 

 The perisarc is bright yellow, and quite smooth. Th& 

 large collar. too, which terminates the perisarc above, and 

 from the bottom of which the uncovered coenosarc rises^ 

 is peculiar. 



The hydranth is distinctly marked off from the stem. 

 and its structure differs from the ordinary conditions in 

 Tiihidaridæ, its diameter, which is quite small between the 

 proximal tentacles, increasing towards the distal end, until, 

 at the oral aperture, it attains a diameter of from <S to 

 Itl \\\m. The structure and arrangement of the tentacle* 

 is similar to those of the other species. 



The blastostyles in this species, on the other haud. 

 are transformed in a manner that is. as far as I know, 

 without parallcl in any other liydroid. I have only had 

 an opportunity of examining theni at an early stage of 

 their development, and it is very possible that their form 

 form in a fully developed condition will not agree with my 

 description of them ; but they ditlVr so greatly in their 

 rudimentary stage from the blastostyles in other Tuhdarklæ 

 that they can hardly entirely lose their individuality. The 

 blastostyles in tlie circle round the liydranth stand so close, 

 that they appear to form a compact ring with a fairly 

 even surface. An examination of the structure of the 

 separate blastostyles shows that they each consist of a 

 very short stem, ramified in the form of an umbel at its 

 distal end, and that each of the 4 or 5 rami immediately 

 expand into a spherical or oval body, whose entire sur- 

 face, with the exception of the part close to the stem, 

 is covered with small round elevations. I have examined 

 the structure of these peculiar formations in a series of 

 sections, and it appears that each of the small rami 

 branching in an umbel from the lower stem, very soon 

 itself forms an umbel. consisting of a number of fine rami- 

 fications, starting from about the same point. The reason 

 Avhy this second ramification cannot l)e seen is tkat the 

 ectoderm is thickened between the rami. and quite fills up 

 the intervening spaces. Tiie gonophores spring from the 



