29 



Knopaiilæg til nye Meduser. 0,2; paa de største ser man 

 endog, hvorledes den ene Radialkaual er sterkere lulviklet 

 enil de ovrige, og man ser i dens distale Væg — hvor 

 den nye Meduses Tentakel vil opstaa — Fortykkelser, der 

 er det første Anlæg til tredie Generation af Meduser. 



Hvor langt disse forskjellige Generationer er konimen, 

 idet ]\roderniedusen løsriver sig, har jeg ikke havt Anled- 

 ning til at nndersoge; men jeg fandt i Ajjril 1897 blandt 

 Plankton i Kristianiafjorden eu Mængde smaa Meduse- 

 kolonier, der uden Tvivl skriver sig fra denne Hydroide. 

 Hos de fleste af disse havde Modermedusen ganske mistet 

 Evnen til at svømme; dens Mauubriuni var meget sterkt 

 iidviklet, omtrent dobbelt saa langt som Klokken, der viste 

 Tverrynker og som i sin forkrøblede Tilstand tydede paa, 

 at denne første Generation af Medusei-ne snart skulde gaa 

 sin Oplosning iraode. Manuliriet smalnede af mod jMund- 

 aabningen til et Rør og havde yderst en omhoiet Kant; et 

 Stykke ovenfor Munden — men udenfor Klokkeranden — 

 saaes et fortykket Belte, der ved Undersøgelse paa Snit 

 viste sig at være Sædet for Generationspi-odukter. 



Svømningen blev paa di-tte Stadium besorget af anden 

 Generations Meduser, og deres Tentakler var atter >S;ede 

 før en Række af senere Generationer paa de forskjelHgste 

 Udviklingstrin. 



Findested. St. 150. 



(V. 0. tSars omtaler (97) at han et Par Gange har 

 iinKU't Tjihula)'ia si)ii2ih'.r, Alder, udenfor Lofoten paa indtil 

 2l.tl) Favnes Dyb. Jeg anser det ikke for urimeligt, at 

 dette har været T. proJiJer. da denne under Xordh.-Exp 

 blev fundet omtrent ved sannne Stod og paa lignende Dyi), 

 og da disse Arter vikle være meget vanskelige at holde ud 

 fra hinanden, naar Blastostylerne ikke er tilstede. Da 

 disse overhovedet ikke er iagttaget hos T. simpJex. er det 

 meget muligt, at denne vil vise sig at være identisk med 

 T. iirolijer. 



Tiibularia? cornucopia. n. sp. 



(Tab. II, Fig. 1). 

 Forelobin- beskrevet, Bonnevie (-!>). 



Trophosome. Ingen Hydrorhiza. Hydrocaulus horn- 

 formet med Spidsen nedad, festet til Stene (jller Skjælfrag- 

 nienter, blank, sterkt gulfarvet uden Ringe eller Stribning. 

 En stor gjennemskinnelig Krave, ca. 10 mm. hoi. afslutter 

 Perisarcen opad. Hydranthen har 30 prøximale Tentakler, 

 ca. 3 cm. lange, og distale, 2 mm. lange, i flere tætstillede 

 Kredse. Dens Diameter tiltager mod den distale Ende, 

 størst ved Mundaabningen. 12 eiendommelig skjærniformede 

 Blastostyler danner en Kreds tæt indenfor de prøximale 

 Tentakler. 



Gonosome. Anlæg som hos de øvrige Tulnilarider; 

 videre Udvikling ukjendt. 



sectional series it appears that these processes are the rudi- 

 mentary Inids of new medusæ; on the largest it can even 

 be seen how one radial canal is more highly developed 

 than the others, and in its distal vvall, at the place whence 

 the WiiW medusa's tentacles vvill spring, thickenings are 

 visible, vviiich are the earliest rudiments øf the third gene- 

 ration of medusæ. 



How far these different genei'ations have advanced 

 by the time tiie parent medusa liecomes detached, I have 

 had no op))ortunity (jf observing; but in Aitril. 1897. I 

 fouud aniong the plankton in the Kristiania Fjord, a num- 

 ber of small medusa colønies, which were without doubt 

 derived from this hydroid. In most of them, the parent 

 medusa had quite lost the power of swimming; its mauu- 

 briuni was very highly developed, being about twice the 

 length of tiie beil whicii exhibited transverse corrugations, 

 and by its shrivelled condition. indicated that this first 

 generation of medusæ were approaching their dissolution. 

 The manubrium v.as narrowed towards the oral aperture 

 to a tube, its edge being deflexed at the extreme end; a 

 little above the mouth. but bcyond the edge of the beil, 

 there was a thickened zone. wliich on exaniination in sec- 

 tion, proved to be the seat of the generative products. 



The swimming at this stage was effected by tlie me- 

 dusa^ of the second generation, aud their tentacles again 

 ■were the domicile of a series of younger generations in 

 the most varied stages of development. 



Locality. Station 150; off Bodø. 



Priif. U. O. Surs says (97) that he has found Tiihii- 

 laria siviplex. Alder, two or three times off Lofoten, at 

 various depths np to 200 fathoms. I think it is not im- 

 probable that this was T. yrolifer, as the latter was found 

 during the N. Atlan. Exp. at about the same place, and 

 at similar depths. and as it would be very difficult to 

 distingnish the two species from one another, if there were 

 no blastostyles. As these have not been observed at all 

 in T. shnplex. it is very possible that this species will 

 prove to be identical with T. prolifer. 



Tubularia? cornucopia, n. sp. 



(,Pi. II, fig. 1). 



Prolimiiiary description. Bonnevie (20). 



Trophosome. Xo hydrorhiza. Hydrocaulus horn- 

 shaped. with the point downwards, attaclied to stønes or 

 fragments of shell; shining, of a Inight yellow colour, 

 without rings or stripes. A large tran.slucent collar. about 

 10 mm. in lieight, terminates the perisarc above. The 

 hydranth has 30 proximal tentacles. about 3 cm. long, and 

 several dense rows of 2 mm. long distal tentacles. Its 

 diameter increases towards its distal end. being greatest at 

 the oral aperture. Twelve peeuliar nmbellar blastostyles 

 form a circle just within that of the proximal tentacles. 



Gonosome. Rudiment as in the øther Tuhularidæ ; 

 suhsequent development unkuow-n. 



