HYDROIDA 2^ 



c 



large tentacle; there are four radial canals. The l)ell exhibits five exumbrellary stinging- cell stripes. 

 The gonophores are developed on eight blastostyles faintly branched, a little more than i mm. long". 



Material : 



Iceland, Reykjavik. Near the shore (i specimen). 



The specimen in hand is one of the original specimens investigated by Scemundsson (1899). 

 It is an individual with hydrocaulus 30 nnn. liigli. The polyp is fitted out with 25 proximal tentacles, 

 5 nnn. long, and 8 blastostyles a little branched, about i nun. long. A closer inquiry of the gonophores 

 gives a picture somewhat different from that drawn from the explanation of Stemundsson. In the 

 first place the umbrella of the medusa is not quite symmetrical, but somewhat oblique, as in Hybucu- 

 doii proli/cr L. Agassiz. At first only one tentacle, not two, is developed on the large tentacle bulb 

 (Tab. II, fig. 16); the "corpora acuminata et duo ovata", mentioned l)y vSccmundsson as springing 

 from the tentacle bulb, are all gems of medusae; none of them can be made out as "initium tentacu- 

 lorum novorum" belonging to the original medusa. Wherever at the first glance two tentacles seem 

 to occur on the bulb, a closer research will show that one of them in fact belongs to the bud of a 

 new medusa on the bulb of the gonophore. Therefore, we have to concur in the opinion of H art- 

 la ul:) (1907) and subscribe to his explanation of the apparent occurrence of two tentacles with Ilybo- 

 odoii proli/cr as satisfactory for the species in iiand, that "bei der Knospung von Hybocodon der Ten- 

 takel in der Eutwickelung stark voraneilt und schon fertig sein kann, weini der dazu gehorige Me- 

 dnsenkorper noch nicht deutlich in die Erscheinung getreten ist". 



The conditions of gonophores described show a much nearer relationsliij) to Tubiilaria [Hybo- 

 codon) Christinac Hartlaub (= Tubiilaria prolifer Bonne vie 1899). Hartlaub's drawing of Hybo- 

 codon Christinac (1907, fig. 98) is, according to the statements cited, easil)' reconcilable to the figure a 

 little more skeletonlike given by S:emundsson (1899, '^^^- ^^i '''&• 3)- ^o'' '■'' '^^^^ difference between 

 the polyps very great; Bonnevie (1899) states for her specimen 14 proximal tentacles, about 10 nnn. 

 long, while the species stated by S;emundsson is said to have 24—30. It is a matter of regret that 

 we only know the length of the proximal tentacles of the specimen in hand. But on account of the 

 great contractility of the tentacles, no particular systematical importance can be attached to their 

 length, and as far as the difference of numbers of the proximal tentacles is concerned, we see in other 

 Tubulariidac within easy reach such a variety that the difference quoted by itself cannot justify any se- 

 paration of species. When Tubiilaria Cliristiiiac is nevertheless maintained as a separate species beside 

 Tubiilaria pulchcr, it is in the first place owing to the express declaration of Bonnevie (1899) that 

 her specimen has no collar under the hydrauth ; such a collar is, on the other hand,'strongly developed 

 in 'Tubiilaria puklicr, though at the first glance it may seem ver}' little distinctive on material preserved.' 



Hartlaub (1907) holds that the medusa is identical with the medusa drawn by Steenstrup 

 (1842), Corync fritillaria, and much is speaking in favour of the correctness of this supposition. On the 

 other hand, the polyp described by Steenstrup, in the same place and by the same name, cannot 

 be identified. It may be that it really is a Corync; some features are even suggestive of Corytic Lo- 

 vcni M. Sars; but the only thing the drawing shows us with full certainty, is that the polyp is no 



I The original specimen of Bonnevies Tubular/a prohfer was wanting in the museum of the Kristiania university. 



