31 



altid kun det ene, enten lutter mandlige eller kvindelige 

 Medusegemmer. De sidste (Fig. 42, 43) udmærke sig ved 

 deres livlige rosen- eller carmosinrøde Farve, som især 

 skyldes de saaledes farvede Æg eller Unger (f, f). Hos 

 de største af disse kvindelige Gemmer bemærkede jeg 

 8—10 opak carmosinrøde Æg eller rettere Unger, da de 

 allerede havde mistet deres Æggehud; nogle af disse 

 sidste vare kugleformige, andre ovale eller elliptiske (~ den 

 saakaldte Planula) og alle omgave i en tæt Klynge den 

 flaskeformige Tap. Andre mindre Gemmer havde færre 

 Æg eller Unger, og atter andre endnu mindre viste kun 

 den indre flaskeformige Tap og slet ingen Æg omkring 

 den (Fig. 39, k, k). 



De mandlige Gemmer (fig. 41) ere kj endelige ved 

 deres blegere, næsten hvide Farve og ringere Stør- 

 relse, idet de kun have en Diameter af \ M.m. Hul- 

 rummet mellem den rosenrøde Tap og den gjennemsig- 

 tige Kappe var hos disse fyldt dels med klare Smaakugler 

 (Spermatozoidernes Udviklingskugler) dels med hvidagtig 

 Sæd, som bestod af lutter livlig sig bevægende Spermatozoi- 

 der med langstrakt-elliptisk Krop og haarformig fin Hale. 



Man ser, at de beskrevne Medusegemmer vise en 

 meget ufuldkommen Medusestructur, idet de af denne 

 kun besidde Kappen og Maverøret (Tappen), men 

 mangle ganske det hele Karsystem saavelsom Rand- 

 traade og Sandseorganer. De staa paa samme lave Ud- 

 viklingstrin som de ganske lignende, man hos Slægten 

 Ciava og mange andre Hydroider harkaidt "Kjønskapsler", 

 og ere saa lidet organiserede, fordi de ikke ere bestemte 

 til at løsrive sig fra Moderdyret og føre et selvstæn- 

 digt Liv. 



Nærværende Hydroide staar af de bekj endte Hydroide- 

 slægter nærmest ved Slægten Heterocordyle Allman, fra 

 hvilken den dog betydeligt adskiller sig derved, at Gem- 

 merne ikke staa paa Siderne af særegne Stilke (Gonobla- 

 stidier), men ere sessile paa den krybende Stolon. Ogsaa 

 med Slægten Rhizogeton Agassiz (Contrib. to the Nat. 

 Hist. of the Unit. States, Vol. 4, p. 224, Tab. 20, Fig. 

 17 — 23) har den nogen Lighed, men adskiller sig ved Hy- 

 droideformens langt større Længde og Smalhed og endnu 

 mere ved dens Tentaklers Stilling, hvilke hos Rhizogeton 

 sidde spredte eller stillede spiralförmig paa Polyphovedet 

 ligesom hos Clava, samt ved den paa den krybende Sto- 

 lon siddende Meduseforms i Forhold til Hydroideformen 

 ringere Størrelse d. e. større Korthed og større Brede. 

 Endelig adskiller den sig fra Slægterne Eudendrium Ehrenb. 

 og Atractylis Wright, med hvilke den ogsaa har adskil- 

 ligt tilfælles ved den meget forskj ellige Form og Anord- 

 ning af Gemmerne. 



Vort Dyr passer saaledes ikke rigtigt ind under nogen 

 af de tidligere bekj endte Slægter, men maa ved dets paa 

 den krybende Stolon fremvoxende sessile Gemmer, som 

 have den samme Form og Anordning hos begge Kjøn, 

 danne en egen Slægt, henhørende til Familien Atractylidæ 

 Hincks. 



on one and the same polyparium; only those of one sex, 

 that is, either all male medusa-buds or all females, being 

 nursed on the same stock. The females (fig. 42, 43) 

 are distinguished by their bright rosy or crimson-red 

 color, which is chiefly attributable to the colored ova or 

 young animals (/ f). In the largest of these female cap- 

 sules I observed 8 — 10 opaque crimson-red eggs, or more 

 properly embryos, as they had already lost their egg-skins; 

 some of these latter were globular, others oval or ellip- 

 tical (the so-called planula) and all of them were closely 

 clustered round the bottle-shaped stud. Other smaller 

 germs had fewer eggs or embryos; and some still smaller 

 shewed only the interior bottle-shaped stud, without any 

 surrounding ova (fig. 39, k k). 



The male capsules (fig. 41) are distinguishable by 

 their paler nearly white color and smaller size, having 

 only a diameter of ^ M.m. The cavity between the rose- 

 colored stud and the transparent mantle, was in these 

 capsules filled partly with pellucid globules (developing 

 globules of the spermatozoids), partly with whitish seed 

 consisting entirely of lively spermatozoids with elongated 

 elliptical bodies and thin filiforms tails. 



It is clear that the medusa-buds here described shew a 

 very imperfect medusa-structure, only possessing the mantle 

 and the manubrium (the stud) and being entirely destitute of 

 the whole vascular system, of the marginal filaments and of 

 the organs of sense. These medusa-buds are in the same 

 low stage of development as those quite similar buds, 

 which in the genus Clava and many other Hydroids have 

 been called "sexual capsules"; and they are so little or- 

 ganised because they are not destined to separate themselves 

 from the parent animal and to lead an independent life. 



Of all the known genera of Hydroids, the present 

 Hydroid stands nearest to the genus Heterocordyle All- 

 man, from which however it differs materially iu that the 

 capsules are not situated on the sides of special stems 

 (Gonoblastidia) but are sessile on the creeping stolon. 

 It has also some resemblance to the genus Rhizogeton 

 Agassiz (Contrib. to the Nat.-Hist. of the Unit. States, 

 Vol. 4, p. 224. Tab. 20, fig. 17—23) but differs in the 

 far greater length and tenuity of the Hydroid form, still 

 more in the position of its tentacles, (which in the Rhi- 

 zogeton are scattered, or placed spirally on the polyp- 

 head, as in the Clava, and also in the smaller size (i. e. 

 less length and greater breadth in proportion to the 

 Hydroid) of the medusa-buds on the creeping stolon. 

 Finally it is distinguisable from the genera Eudendrium 

 Ehrenb. and Atractylis Wright, with which it has several 

 points of resemblance, by the widely different form and 

 arrangement of the buds. 



Our animal can not therefore suitably be classed 

 under any of the hitherto known genera, but must, by 

 reason of its sessile buds, growing out of the creeping 

 stolon and having the same shape and arrangement for 

 both sexes, form a separate genus belonging to the fa- 

 mily Atractylidæ Hincks. 



