REPORT ON THE SIPHONOPHOR^E. 233 



Genus 47a. Halistemma, 1 Huxley, 1859. 



Halistemma, Huxley, Oceanic Hydrozoa, pp. 70, 129. 



Definition. — Agalmidse with a long and movable siphosome, the trunk of which 

 is very contractile; bracts with large intervals. Cormidia loose; palpons and gono- 

 styles on the internodes scattered between the siphons. Tentilla with a naked cnido- 

 band and a simple terminal filament. 



The genus Halistemma was established by Huxley in 1859 for that Mediterranean 

 Agalmid, the first description of which Vogt had published under the name Agahna 

 rvbrum (6, Tab. vii.-xi.). Perhaps identical with this species (from Nice) is another 

 Mediterranean form, which Kolliker has figured under the name Agalmopsis punctata 

 (4, Tab. iv.). Succeeding observers have described many different Agalmidse as 

 Halistemma, and mainly those forms which belong to the following genus Cupulita. 

 But the true Halistemma, according to the definition given by Huxley, differs from all 

 allied Agalmidse in the simple structure of the tentilla, which have the same form as in 

 Forshalia (PL IX. fig. 7, t ; PL X. fig. 23). The naked cnidoband is a simple spirally 

 convoluted riband without involucre, and bears a simple terminal filament. In all 

 other respects Halistemma* seems to agree with Cupulita ; but perhaps both genera 

 differ also in the structure of the palpons, which in the former seem to be mouthless, in 

 the latter provided with a terminal mouth (cyston). 



Genus 47b. Cupulita? Quoy and Gaimard, 1824. 

 Cupulita, Quoy et Gaimard, Voyage de l'Uranie, &c, p. 580. 



Definition. — Agalmidse with a long and movable siphosome, the trunk of which is 

 very contractile ; bracts with large intervals. Cormidia loose ; palpons and gono- 

 styles on the internodes scattered between the siphons. Tentilla with an involucrate 

 cnidoband and a simple terminal filament. 



The genus Cupulita was founded in 1824 by Quoy and Gaimard for an Agalmid, 

 which Gaudichaud had captured at Port Jackson. The description of their Cupulita 

 bowdichii (19, pi. lxxxvii. figs. 14-16) is very incomplete; but the figure which they 

 give of the nectosome is so similar to that of Halistemma tergestinum and some closely 

 allied species, that we employ the older name for these latter, instead of giving a new 

 name. Cupulita is in all respects very similar to the true Halistemma (rubrum or 

 punctatum), but differs in the form of the tentilla ; the spiral cnidoband is not naked 

 (as in the latter), but enveloped by a campanulate involucre. Another difference is 

 perhaps marked by the structure of the palpons, which in Cupulita are true excretory 



1 Halistemma = Marine corona, ahiat;, oTtfiftx. 2 Cupulita = Beset with cupules. 



(zool. CHALL. EXP. — part lxxvii. — 1888.) Hhhh 30 



