194 Prof. Carl Glaus on the 



starting-point of the production of the Siphonophore was 

 recognized. 



Consequently the two theories no longer stood by any 

 means in direct opposition, as the Poly organ- and Poly per son- 

 theories, and were also brought nearer together in that in the 

 case of the latter the derivation from the Hydi*oid Medusa 

 might be accepted. Ah-eady it was attempted to clear up the 

 mixture of truth and error, although in a different form and 

 direction from HaeckeFs Medusome-theory, and, indeed, in 

 favour of the Hydroid-theory, wliich regards the Siphono- 

 phora as " swimming Hydropolyp-stocks " and deduces the 

 resemblance of the larvee to Medusee from cEenogenetically 

 altered conditions. It was necessary to modify the original 

 conception formulated by R. Leuckart only so far that in the 

 room of the Hydroid-stock which after separation from its 

 support adopted the pelagic mode of life and acquired a hydro- 

 static apparatus at its base now turned upwards, the swimming- 

 larva, prevented from fixing itself but not affected iu its 

 nutrition, was placed, and, in agreement with the recently 

 established views as to relation of the Medusa to the Polyp, 

 the derivation of the Siphonophore from the Medusa as the 

 sexual animal of the Hydroid-stock was recognized. 



As regards the new Classification of the Siphonopliora, on 

 which Haeckel has based his work, its specialities follow 

 directly as consequences of his hypothesis of diphyletic 

 origin. The Siphonophora are raised into a class, and 

 divided into two legions or subclasses with reference to their 

 binary origin : — 1. The SirnONANTHJi, derivable from the 

 hypothetical Protomeda ; and 2. The Disconanth^, origi- 

 nating from the hypothetical Archimeda. The first subclass 

 is divided into the ordinal sections Calyconectce, Physonectce^ 

 and CystonectcB, which correspond to the previously recog- 

 nized groups Calycophoridce^ Physophoridce, and Physalidce^ 

 to which are added, as a fourth order, i\\Q AuronectcBj a group 

 of exceedingly remarkable deep-sea forms previously unknown. 

 The second subclass contains the single order Disconectce^ 

 wliich corresponds to the fourth Siphonophoran group, known 

 as Ghondrophoridce or Discoideie. As the assumption of a 

 special stem-form for the Discoideaj, which may be easily and 

 naturally derived from the Physophoridie, seems neither 

 necessary nor well founded, the alteration of the system 

 founded upon it, which places the Discoidege in an equivalent 

 relation to the whole of the other groups, will have to be 

 rejected as a novelty by no means justified by the state of the 

 case. And we aannot deal otherwise with the many new- 

 denominations by which Haeckel, following his previous 



