har tillngt dette nogeii større Betydning. Merkelig noic er 

 Udviklingen af Blastostylerne ellers ikke tåget i Betragt- 

 ning i Systematiken, og jeg vil derfor ikke undlado at gjøre 

 opmerksoni paa den som paa en Rettesnor, der efter min 

 Opfatning maa lede til Bygningen af et naturligt System. 



De forskjellige Familiers Afstamming i dette System 

 tænker jeg mig saalodes. som antydet i Fig. 1. 



iie has attrihuted to it any great importance. Strange to 

 say, the development of the blastostyles it otherweise not 

 tåken into consideration in the systematisation; and there- 

 fore I cannot omit to point to it ;is to a guide which. in 

 my ()i)inion. must lead to tlie construction of a natural 

 system. 



T takr the dcrivaticju of tlie various families in this 

 system to lic as sliovn in fig. 1. 



Corynidae 



Fi!?. 1. 



-Myriothelidae 

 ""Tubularidae 



-Clavidae ^..,-— "Eudendriidae ^^-^Plumularidae 



Bougainvillidae Haleciidae 



^^Campanularidae 



Sertularidae 



ScJineider har gjort oi)merksom paa det unaturhge i 

 at stille Claiidae som Udgangspunkt for alle de athecate 

 Hydroider. (hvad tidligere altid liar været gjort). Coryni- 

 dae. der har kolleformede Tentakler kan neppe stamme fra 

 Arter med traadformede. da Udviklingen af Tentaklerne 

 andensteds i Systemet gaar i den modsatte Retning (Over- 

 gang fra Coryne til Pennarid). Han lader imidlertid uaf- 

 gjort, livorvidt Clavidae har sin Oprindelse i Corynehvmev, 

 eller om begge disse Familier, der hver for sig danner 

 Udgangspunkt for en Række andre, har sit Udspring i 

 endnu ukjendte Former. Jeg er enig med Sclineider i, at 

 begge disse Opfatninger har lige niegen eller iige liden 

 Støtte i de hidtil kjendte Fakta, og jeg felger ham derfor 

 ved foreloblg at indordne Hydroidefamilierne eiter to for- 

 skjellige Linier med Ildgangspunkter respektive i Fam. 

 Cory)iidae og Clavidae. 



Inden Fam. Corynidae findes en Udvikling i to Ret- 

 ninger, mod MyriofheVnlae (kun representeret ved en enkelt 

 Form C. giqantea), og mod Tnhnlaridae. Paa Overgangen 

 til denne Familie har tidligere staaet Fam. Pennuridae 

 karakteriseret derved, at Hydrantherne havde baade traad- 

 formede og kolleformede Tentakler. Srlmeidev har opløst 

 denne Familie, eller rettere sagt, han har stillet en Del af 

 dens Slægter over i Fam. Corynidae, og paa den anden 

 Side har han indlemmct i den alle TahuJaridae. Jeg er 

 enig i, at Fam. Pennaridae ikke kunde blive staaende i 

 sin oprindelige Skikkelse, men idet nogle af dens Arter 

 henføres til Cory)iidae, og de øvrige til Tnhularidae, opløses 

 den jo af sig selv, og jeg linder ingen Grund til at foran- 

 dre Navn for Fam. Tiibnlaridae, fordi om man henfører 

 til den endel Arter, der tidligere har tilhørt Pennaridae. 



I Principet for Delingen af denne Familie er jeg 

 heller ikke ganske enig med Schneider. Han henfører til 



Sclnicider has drawn attention to the fact of its being 

 unnatural to set up, as has ahvays hitherto been done, 

 Clavidæ as the starting-point for all the athecate hydroids. 

 Corynidæ, which have clavate tentacles, can scarcely be 

 derived from species wiht tiliform tentacles, as the devel- 

 opment of the tentacles elsewhere in the system goes in 

 the opposite direction (transition from Coryne to Pennaria). 

 Schneider, however, leaves nndetermined the question whe- 

 ther Clavidæ have arisen from Coryne forms, or whether 

 both families, which each form the starting-point for a 

 number of others, originate in hitherto iinkown forms. I 

 agree with Schneider in consideiing that øne of these theo- 

 i-ies has as much or as little support as the other in the 

 hitherto known facts, and I therefore follo^y him in a 

 temporai'y arrangement of tlie hydroid families in two dif- 

 ferent lines, starting \vith the families Corynidæ and CJaridæ. 



ln the family Corynidæ, tliere is a development in 

 two directions, towards Myriotlielidæ (only represented by 

 a single form, C. gigantea), and towards Tuhidaridæ. The 

 family Pennaridæ has hitherto been the transitional link 

 beween the two families, and has been characterised by 

 the circumstauce that the hydranths had both filiform and 

 clavate tentacles. Schneider has broken up this family, or 

 rather he has placed some of its gerera in the family 

 Corynidæ, and on the other hand has incorporated in it 

 all the Tidndaridæ. I am also of opinion that the family 

 Pennaridæ could not remain in its original form; hut in 

 referring some of its species to Corynidæ, aud the remainder 

 to Talndaridæ, it dissolves itself; and I see no reason for 

 changing the name of the family Ttdndaridæ, Ijecause a few 

 species are referred to it which have formerly belonged 

 to Peiniaridce. 



Nor do I quite agree Avith ScJtneiders principle in 

 tlie divisiou of this family. To Corynidæ he refers Stau- 



