18 



sig da los fra Kolonien, og forst efter denne Adskillelse 

 opstaar hos dem Generationsstoffe. Imidlertid lindes, hos 

 enkelte Arter, Gonoforer, med fuldstændig Medusebygning, 

 men som, eiidnu medens de staar i Forbindelse med Kolo- 

 nien, forsynes med Generationsstoffe; jeg tror det kan nd- 

 tales som en Regel, at disse Gonoforer aldrig kommer til 

 at løsrive sig fra sin Koloni; thi samtidig med at Genera- 

 tionsstoffene udvikler sig, forkrøbles Meduseklokken, og 

 Gonoforernes Rolle er udspilt, naar Yngelen har forladt 

 den. En saadan merkelig Overgangsform mellem de fri 

 Meduser og de fastsiddende Gonoforer, findes inden Tubu- 

 laridernes Familie lios Cori/morpha sarsii, medens Arter 

 som Ttihidaria jirolifer, Corymorplia mdans o. s. v. har 

 fuldstændig fri Meduser. 



Medens Gonoforerne hos alle de her nævnte Arter 

 representerer forskjellige Udviklingstrin af en og samme 

 G)'undform, er de pseudoiufi(hiso/de (ronoforer hos Slægten 

 Lampra bygget efter et andet Princip. Anlægget af 

 j.Glockenkern" ei- her det samme som hos de medusoide 

 Gonoforer; men istedetfor at Ektodermindlnigtningen hos 

 disse skyver Entodermen foran sig og derved bevirker den 

 karakteristiske Foldning af denne, saa vandi-er den i Lani- 

 jjra-Arternes Gonoforer lielt ind i Entodermen og ])aa denne 

 Maade blir kun et enkelt Entodermlag liggende mellem 

 „Glockenkern' og Ektoderm og Muligheden for Dannelse 

 af Radialkanaler er herved udelukket. Heller ikke sker 

 der nogen Spaltning i to Lag blandt de indvandrede Ek- 

 todermceller, og man finder saaledes intet andet Hulrum i 

 Gonoforerne end den smale Kanal, som strækker sig op gjen- 

 nem Spadix. Foruden hos alle de kjendte Arter af Slægten 

 Lumpra, findes saadanne Gonoforer ogsaa iios de forskjel- 

 lige Mi/riothela- Avtev. De findes paa Figuren illustreret 

 ved den overste Række af schematiske Snit. 



I Nordh.-Exp.'s Materia 

 jende Arter : 



findes af denne Fam. føl- 



Gen. Lampra. 



Lampra sarsii, n. sp. 



(Pl. II, Fig. :i). 



Forelobin; Beskrivelso, Bonnevie (29). 



Trophosotne. Hydrocaulus 8—10 cm. lang, purpur- 

 farvet med mørke Lrengdestriber, og en Masse fine Hefte- 

 traade i den proximale Ende. Ingen skarp Overgang til 

 Hydranthen, som har ca. 10 proximale Tentakler, 1 — 2 cm. 

 lange, og distale Tentakler i flere vel adskilte Kredse. 

 Ca. 10 Blastostyler, 4 — 6 mm. lange og med et betydeligt 

 Hulrum i hele sin Længde, danner en Krods tæt indenfor 

 de proximale Tentakler. 



GonoBome. Fastsiddende pseudomedusoide Gonoforer 

 med en rudimentær Tentakel; flere Æg udvikles i hver 

 af dem. 



tiiey then detach tiiemselves from the colony; and it is 

 not until after this separation tliat reproductive elements 

 appear in them. In certain species, however. there are 

 gonophores witii a complete medusa-structure, but provided 

 witii reproductive elements while still connected with the 

 colony. I think it may be stated as a rule tliat these 

 gonophores never ])ecome detached from their colony; for 

 with tile develoj)inent of tlie generative products. there is 

 a shrivelling of the medusa-bell, and the part of the 

 gonophores is played out when the young have left it. A 

 remarkable transition-form such as this between the free 

 medusæ and the fixed gonophores, is found in the Tiihn- 

 Jaridæ in Cori/moi'pha sarsii, while species like Tnhularia 

 prolifer. Cori/morpha nutrnis. etc. have entirely free medusæ. 

 While the gonopliores in all the species here named 

 represent difterent stages of the development of one funda- 

 mental form, the pscudo-iiiedusoid gonopliores in the genus 

 Ldmpra are constructed ou another principle. Tlie rudi- 

 ment of the 'glockeiikern' is the same tliere as in the 

 medusoid gonophores, but whereas. in the latter, the inva- 

 gination of tlie ectoderm pushes tlie endoderm before it, 

 tims producing its characteristic folding, in the gonophores 

 of the Lampra species it penetrates (piite into the endo- 

 derm, and in this way, only a single endoderm layer is 

 left between tlie 'glockenkern' and the ectoderm, aud all 

 possibility of the formation of radial canals is thereby 

 excluded. Nor does any division into two layers take 

 place amoug the iu-wandering ectoderm cells, and thus no 

 cavity is to l>e fouud in tlie gonophore liut tlie narrow 

 canal running up tlirough tlie sjiadix. Gonophores of this 

 kind are found not only in tiie known species of tiie genus 

 Lampra. but also in the various Myriothéla species. They 

 will be found in fig. illustrated liy the upper row of dia- 

 grammatic sections. 



Among tiic bydroids from the X. Atl. Exp. the fol- 

 lowing Tnbularidae where found: 



Gen. Lampra. 



Lampra sarsii, n. sp. 



(i'i. II. tig. :;). 



Preliminary descriptiou, Bonnevie (29). 



Trophosome. Hydrocaulus 8 — 10 cm. in length, 

 colour purple, with dark longitudial stripes; and a number 

 of fine attaching filaments at its proxinial end. No sudden 

 transition to the hydraiith, wiiich has aljout 10 proxinial 

 tentacles, from 1 to 2 cm. in lengtii, and distal tentacles 

 in several clearly-marked circles. About 10 blastostyles 

 from 4 to G mm. in length, forming a circle just within 

 the ring of proxinial tentacles, and with a considerable 

 cavity extending throughout their length. 



Gonosome. Fixed pseudo-medusoid gonojiiiores with 

 one rudimentary tentacle; several eggs are developed in 

 each gonopiiore. 



