Corynidae: Stanr/diiini, HaJocliaris, Cladonema, Cladoco- 

 ryne, — og til Tuhularidae (Pennaridae), Pennaria, Accmlis, 

 Heteroste.phnnu» o. s. v., idet han lader de traadformede 

 Tentaclers Udvikling liestemme Grænsen mellem Familierne. 

 Jeg tinder imidlertid ikke Spranget storre mellem Arter 

 med korte traadformige Tentakler (Staiir/diuui) og saa- 

 danne med lange (Peniiaria). end det er mellem en alniin- 

 delig Coryne med kun kolleformede Tentakler og f. Eks. 

 en Stanridimn; begge Forandringer i Tentaklernes Bygning 

 er Skridt i en Udvikling fra Coryne mod Tuhtlaria, og 

 SrJiitciders Grænse mellem disse to Familier forekommer 

 mig derfor meget vilka årlig. Jeg tinder det naturligere at 

 henregne til Corynidai' alle de Arter, der bærer Tentaklerne 

 spredt eller siddende i Kredse jevnt fordelt over Hydran- 

 then, medens alle Tuhidaridai' har sine Tentakler anordnet 

 i to skarpt adskilte Kredse paa lienholdsvis den proximale 

 og den distale Del af Hydranthen. Ved at betragte de 

 to Grupper, hvor Fam. Pennaridae efter dette maa deles, 

 ser man at der ogsaa i andre Retninger er Overensstem- 

 melse mellem Arterne inden hver af disse Grupper. Til 

 Corynidae maa henregnes, foruden do af Sc/ineider nævnte 

 Arter, ogsaa Pennaria og Acaidis, og alle disse har lange, 

 kegleformig tilspidsede Hydranther og Gonophorerne sid- 

 dende paa Hydranten, medens Heter odephanus (Vortidava 

 og Acliaradria), der maa henregnes til Tuhularidae, stem- 

 mer fuldstændig overens med disse i Hydranthernes Byg- 

 ning, idet den i)r(ixiniale Del er sterkt udvi(h't saa at dens 

 diameter omtrent er lig Hydrantliens Længde, — og Heiero- 

 f^tejdianus slutter sig til denne Familie ogsaa derved, at 

 dens Gonoforer bæres paa Blastostyler, der sidder i en 

 Kreds indenfor de proximale Tentakler. 



Angaaende J\TyriotJiela's Stilling som en selvstændig 

 Familie, har jeg nedenfor anfort mine Grunde for denne 

 Opfatning. 



Den anden Gren af de athecate Hydroider med Ud- 

 gangspunkt i Clavidae, danner en temmelig tæt sluttet 

 Række af Slægter, som tidligere har været stillet i mange 

 forskjellige Familier. Levinsen luir (79) reduceret disses 

 Tal betydelig, idet han under Fam. BouyainvilJidae sam- 

 mensluttede alle Arter med traadformede Tentakler stillet 

 i en Kreds, og Schneider er gaaet endnu videre, nendig 

 ved at henfore alle disse til Fam. Clavidae, idet han dog 

 giver Eudendridae Plads som en Familie for sig. 



Naar han saaledes under Fam. Clavidae sammenfatter 

 Arter med spredte Tentakler og saadanne, der har Ten- 

 taklerne stillet i en Kreds, — da forekommer det mig, at 

 lian gaar for vidt med Hensyn til' Forenkling af Systemet. — 

 Selv om Tentaklerne hos enkelte Arter af Boaf/ainriUidae 

 ikke kan siges at staa kun i en Kreds, (som hos Periyo- 

 nimusj, saa er de dog her overalt samlede paa et forholdsvis 

 lidet Parti af Hydranthen ; og Forholdet er her et ganske 

 andet end hos de forskjellige C7«rfl-Arter, hvis Tentakler 

 sidder jevnt fordelt over hele Hydranthen; og man vil 

 neppe nogeusinde være i Tvivl om, til hvilken af de to 

 Grupper en Hydranth skal henregnes. De øvrige Fami- 

 lier blandt de atliecale Hydroider, karaktiseres ogsaa ved 

 Tentaklernes Forhold, og de Klofter, der adskiller dem. 



ridiani, Haloeliaris, Cladonema, and Cladocorynic: and to 

 Tuhnlaridæ (Pe)inaridæ), Pennaria, Acaidis, Heteroste- 

 plianus. etc, letting the development of the filiform tentac- 

 les determine. the bnundary lietween the families. I do 

 not however, consider the break between species with siiort 

 filiform tentacles (Siauridiani), and those with long (Pen- 

 naria), greater than that l)et\veen an ordinary Coryne witii 

 only clavate tentacles, and a Stauridiurn, for instance; hoth 

 the changes in the structure of tlie tentacles are stages in 

 a development from Coryne to Tubnlaria. and therefore 

 Schneiders boundary between these two families seems to 

 me to be a very arl^itrary one. I consider it more natural 

 to refer to Corynidæ all tl)ose species wliose tentacles are 

 scattered or arranged in rings evenly distributed over the 

 liydranth, %vhile all Tuhnlaridæ have their tentacles arran- 

 ged in two distinctly separated rings, one on the proximal, 

 and the other on the distal portion of the hydrantii. On 

 looking at the two groups into which. aceording to tliis, 

 the faniily Pennaridw must be divided, it will be seen that 

 in other particulars too, tliere is a similarity l)etweeu the 

 species in each of these groups. In addition to the spe- 

 cies naraed by ScJineidei: Pennaria and Acauli< must be 

 referred to Corynidæ. and all these havel ong, connically- 

 pointed hydrantlis. and the gonophores attached to tlie 

 hydranth; while Heferosteplianas (Vorticlava and Acliara- 

 dria). wliich must l)e referred to tlie Tuhnlaridæ. agrees 

 perfectly with them in the structure of the hydrantlis. their 

 proximal part l)eiiig greatly expanded. so tliat its diameter 

 is about equal to the length of the hydranth, aud this species 

 also goes witli the Tuhnlaridæ. from the fact of its gono- 

 pliores being upon blastostyles which are arranged in a 

 circle within that of the proximal tentacles. 



My reasons for regarding Myriothela as an indepen- 

 dent faniily are stated below. 



The other hranch of athecate hych-oids, with Clavidæ 

 as its starting-point, forms a fairly coinpact series of genera, 

 whicli have formerly been placed in maiiy different families. 

 Levinsen (79) has reduced the nuinber of these considerably. 

 uniting under the family Bouyainvillidæ all species with 

 filiform tentacles arranged in a ring; and Schneider has 

 gone even further. and referred them all to the family 

 Clavidæ, although he gives Eudendridæ a place by itself. 

 as a separate family. 



"When Sclineider thus comprises in the family Clavidæ, 

 species with scattered tentacles, and species with the ten- 

 tacles arranged in a ring, it seems to me that he goes too 

 far with regard to the simplification of the system. Even 

 if the tentacles in certain species of Bouyainvillidæ cannot 

 be said to stand only in a ring (as in Periyoniinns). yet 

 they are always congregated on a comparatively small por- 

 tion of the hydranth, and the conditions here are quite 

 different to those in the various Clava species, where the 

 tentacles are evenly distributed over the whole hydranth; 

 and there will hardly ever be a doubt as to which of the 

 two groups a hydrantii is to lie referred to. The remaining 

 families among the athecate hydroids are also characterised 

 by the position of the tentacles; and the gaps which sepa- 



