48 



ACALEPIIS IN GENERAL. 



Part I. 



Fij. 22. 



Fig. 23. 



Medusa CAMPAjiULA,Fabr. 



Medusa campamula, Fabr. 



(A 5|)ecies of Melicertum Wen, seen fiom 

 above.) 



The free MeJusa of a very common Sertu- 

 lnri;ui Hydroid of the Atlantic coast of Xorth 

 America. 

 tn Miiuth. — oo Ovaries along the vertical chy- 



mif.nius tubes— ((( Tentacles. 



Tliaumantiiis {Fig. IT) or Melicertiuu {Figs. 22, ami 23), which are rosjioctivel}- the 

 free Medusae of a Coryne {Fig. 19), a, Tuhulariau {Fig. 11), a Campanularian {Figs. 10 

 and IG), and a .Sertuhirlan {Fig. 18). And if we compare the Cor^yne with the Tubu- 

 laria, the only e.s.sential diflerenee we notice i,>^, that while in Tubularia the feelers 



are arranged in a- whorl around the 



base of the proboscis, in Coryna 



they are scattered all over the 



proboscis. 



There is only one more group 



of animals that has been as.sociated 



with the Medusa?. I mean the 



(A species of Melicertum Acalepkcs kl/drOStatiqilCS of Cuvicr, 

 Ofe»i, seen in profile.) i rj ^ 



The free Medusa of a very Called Sij^JlOnopkorW Ij}' Esclisclioltz 

 common Sertularian Ily- n Ji , ■, t~\ 



droid of the North Anioii- ^in'l ^hc morc recent writcr,^. l^roin 

 '=^°"™''- the time they l^ecame first known 



t Tentacles. — o Ovaries, along 

 the vertical chymiferous tubes. tlirOUiill tllC (IcSCriptimiS of Foi'skal 

 — m Mouth. — a Disc. '^ ■■■ 



and the si>lendid illustratiuns of 

 LeSueur, they have always been considered as allied 

 to the Medusa^, until recently Kulliker has associated them with the Polyps under 

 the name of swinuuing Polyps, Ptilgpi Nechulei. An opinion expressed without 

 hesitation liy so eminent an investigator as KiJlliker requires the most careful 

 examination. To arrive at a satisfactory result on this critical point, it is neces- 

 sary, in the first place, to ccmsider the fact, that the so called swimming Polyps, the 

 Siphonophora? of most authors, are compound animals, — that is to say, communities 

 of individuals organically connected in a manner similar to the connnuuity tliat 

 exists between the numerous individuals of a Coral stock or of a Hydroid stock. 

 But this is not all. The individuals so connected in these connuunities have no 

 more the same apiiearance than those of the communities formed liy certain Ily- 

 droids ; and that we may lie the Ijctter prepared to appreciate the extraordinary 

 extent to which diflerent individuals of the same community may difler in a stock 

 of so called swiunning Polyps, it may lie well to consider lieforeliand the extent 

 of the ditferences we oljserve lietween the individuals of similar stocks among 

 genuine Polyps, as Avell as among Ilydroids. 



In a Polyp community the rule is, that all the individuals of the same stock 

 resemble one another in every resju'ct, differing slightly in size, and, it may be, 

 as in the confiuent s}iecies, in the nundjcr of mouth.s circumscribed by a con- 

 tinuous series of tentacles, as for instance in Ma\andrina, Dijiloria, Gyrophyllia, 

 Manicina, etc. In some of the Madrepores, however, and especially in those which 

 produce numerous distinct branches, there is a greater difference, each branch 



