20 



II. BESKRIVELSE OVER STEENSTRUPIA 

 GLOBOSA. 



EN NY ART AF DE LAVERE MEDUSER. 



(Tab. 1, Fig. 1—6.) 



Steenstrupia gldbosa. Sars, Christiania Vid. Selsk. Forh., 1859, 



paöf. 101. 



TV/fed dette Navn har jeg paa ovenanførte Sted kortelig 

 •*■-*- charact eriser et en liden fritsvømmende Meduse, som 

 viser saa megen Lighed med nogle af de af Corymorpha 

 opammede Medusegemmer, at det forekommer mig sand- 

 synligt, at den stammer fra en Art af denne Ammeslægt. 



At den maa henføres til den af Forbes (Monograph of 

 the British naked-eyed Medusæ pag. 72) opstillede Slægt 

 Steenstrupia, kan vel neppe være tvivlsomt, uagtet den 

 ikke ganske svarer til de af Forbes givne Slægtscharac- 

 terer. Skiven eller Kappen er nemlig ikke "conisk til- 

 spidset", men rund hvælvet; der er ingen "forbindende 

 Streng (chord) fra Apex til Subumbrella", og endelig fin- 

 des ikke blot a én enkelt", men 3 Randtraade udviklede 

 fra den ene af de 4 Randbulber. Disse Forskjelligheder 

 kunne dog neppe betragtes anderledes end som specifiske; 

 ja Tilstedeværelsen af en "Streng indeni Apex" synes 

 saameget mindre at burde bibeholdes som Slægtscharacter 

 som den neppe engang er constant for Arten, idet denne 

 Streng vel ikke er noget andet end en Levning af Ernæ- 

 ringskarret, som i den forrige fastsiddende Tilstand for- 

 bandt Medusegemmen med dens Ammedyr. Formodentlig 

 have de to af Forbes beskrevne Arter, S. rubra og S. 

 flaveola, som vise denne Streng, først nylig været afløste 

 fra deres Ammedyr; hos vor norske Art fandtes ikke 

 Spor af den. 



Steenstrupia globosa er 2^ M.m. lang og 3 M.m. bred, 

 dens Randtraade i fuldt udstrakt Tilstand mere end 20 

 M.m. lange. Den adskiller sig (Fig. 2, 3) ved første Øie- 

 kast fra hine 2 brittiske Arter ved dens bugede, kort- 

 klokkeformige, næsten kugledannede Kappe (Umbrella 

 Forbes), hvis forreste ganske lidt firkantede Rand er 

 skjævt afskaaren, idet den rager noget længere frem eller 

 er noget høiere i det Hjørne, hvor Randtraadene sidde. 

 Denne Kappe (a) er aldeles farveløs eller vandklar, glat 

 og jævntyk, idet dens indre hule Flade (Subumbrella For- 

 bes (b) har samme Form som dens ydre Contur; dens 

 bageste Ende, Toppen (Apex) eller Kuppelen er jevnt 

 tilrundet, ikke conisk eller tilspidset som hos hine brittiske 

 Arter, men i denne Henseende overensstemmende med 

 den af Steenstrup (Ueber den Generationswechsel pag. 22, 

 Tab. 1, Fig. 43—45) iagttagne, af Coryne fritillaria Stp., 

 opammede Meduse, hvis nære Beslægtskab med hine ogsaa 

 Forbes selv har erkjendt (1. c, pag. 72). 



Fra Bunden af Kappehulen (Svømmehulen) hænger, 

 ligesom Kolben i en Klokke, den cylindriske eller tenfor- 

 mige Mave (Fig. 2, 3, c, Fig. 4) frit ned. Denne Mave, 

 som forresten antager forskjellige Former efter dens for- 

 skjellige Contractionsgrad og ofte stærkt forkortes, hvor- 

 ved den bliver saameget tykkere, er blodrød, har tykke 

 Vægge, en efter dens ydre Contourer dannet indre Hule, 



II. DESCRIPTION OF STEENSTRUPIA 

 GLOBOSA. 



A NEW SPECIES OF THE LOWER MEDUSÆ. 

 (Tab. 1, fig. 1--6). 



Steenstrupia globosa, Sars, Christiania Vid. Selsk. Forh., 1859 



page 101. 



have in the above mentioned work, thus named and 

 -*- shortly characterised a small freely-swimming Medusa 

 which so much resembles some of the gonozooids fostered 

 by the Corymorpha, that I consider it as very probably 

 the offspring of some species of this genus. 



That it may be referred to the genus Steenstrupia 

 established by Forbes (Monograph of the British naked- 

 eyed Medusæ, page 72) can scarcely be doubted; although 

 it does not exactly answer to the generic characteristics 

 given by Forbes. The disc or umbrella is not "conically 

 pointed" but rounded; there is no "connecting chord 

 from the apex to the subumbrella"; and finally not only 

 "a single" but 3 marginal filaments are developed from 

 one of the 4 marginal bulbs. These differences can 

 however scarcely be regarded as more than specific; nay 

 the presence of a "chord within the apex" does not ap- 

 pear retainable as a characteristic of genus; seeing that 

 it is not even constant in the species; this chord being 

 probably nothing but a remnant of the alimentary vessel, 

 which connected the gonozooid, in its previous attached 

 state, with the parent animal. Probably the two species 

 described by Forbes, S. rubra and S. flaveola, which ex- 

 hibit this chord, had been recently disconnected from their 

 parent: in our Norwegian species, there was no trace of 

 any such chord. 



Steenstrupia globosa is 2^ M.m. long, and 3 M.m. 

 wide; its marginal filaments fully extended are more than 

 20 M.m. long. It is distinguished (fig. 2, 3) at first 

 glance from the 2 British species, by its swollen short- 

 bell-shaped nearly globular umbrella, the anterior 

 slightly squared margin ol which is obliquely truncated, 

 projecting somewhat more, or being a little higher at the 

 corner, where the marginal filaments are situated. This 

 umbrella (a) is quite colorless or pellucid, smooth and 

 of even thickness; its interior hollow surface (subum- 

 brella Forbes) (b) having the form of its outline; its 

 posterior extremity, (apex) or cupola is evenly rounded, 

 not conical or pointed as in the British species referred 

 to, answering in that respect to Steenstrup's description 

 (über den Generationswechsel, page-22, tab. 1, fig. 43—45) 

 of the Medusa fostered by the Coryne fritillaria Stp., 

 of which also Forbes himself has recognised the close 

 relationship to the British species (1, c, page 72). 



From the bottom of the cavity of the umbrella (the 

 swimming cavity) there hangs, like the clapper of a bell, 

 the cylindrical or fusiform stomach (fig. 2, 3, c, fig. 4). 

 This stomach, — which moreover assumes various forms 

 according to its different degrees of contraction, and is 

 often considerably shortened, whereby it becomes so much 

 thicker — is blood-red; it has thick walls, with an 



