(iiul their Iteiatiuntihij) to the Cural.s. 7 



Medusae) ; 3. Ctenopliora (Ciliograda), All the animals of 

 tiiese three classes agree not only in the characteristic formation 

 of the nutritive vascular sjstem, but also in the possession of 

 urticating organs, for which reason Huxley grouped them to- 

 gether as Nematophora. These characteristic urticating organs 

 are entirely deficient in all true s])ongcs. The absolute deji- 

 ciency of the urticating otyans in all sjwnr/es, and their constant 

 presence in all corals, Hydromedusa3, and Ctenophora, is at 



S resent the sole morphological character which sharjily and 

 ecidedly separates the first class from the last three. I have 

 therefore, in my ' Monograph of the Monera,' and subsequently 

 in my ' Natural History ot Creation,' included the three last- 

 mentioned classes under the old name of Acalejjha' or Cnidce 

 (nettle-animals). Even Aristotle comprehended under this 

 denomination the two characteristic primary types of the 

 group, the free-swimming Medusoi and the sedentary Actimce. 

 Moreover the distinctive character of the nettle-animals, 

 namely the possession of urticating organs, is just as clearly 

 expressed by this denomination as by Huxley's name Nema- 

 tophora. 



We should therefore have to divide the stem or phylum of 

 the Zoophytes {Coelenterafa s. Zoojihijta) into two primary 

 groups (subphyla or cladi) — 1, Sponges {Spongice s. Pori- 

 fera)j and, 2, Nettle-animals {Acalej)hip, s. Cnidiv, s. Nemato- 

 phora). The latter would divide into the three classes of the 

 Corals, Hydromedusje, and Ctenopliora. Among the sponges 

 we might j)rovisionallf/ distinguish as two classes the Auto- 

 sj)on(/ia} and the fossil Petrosjjongioi, as hitherto these two 

 groups have not allowed themselves to be brought into near 

 connexion either in the whole or in detail. Among the Auto- 

 spongise the Calcispongite would form a distinct subclass or 

 legion. 



We might perhaps go even further, and, suppoi'ted by the 

 very near relations of affinity of the sponges and corals, speak 

 in favour of the following division of the Coelenterata : — 



Cladus I. Bush-animals (Thamnoda). 



Class 1. Sponges (Sjjoyigice) . 

 Class 2. Corals {Corallia). 



Cladus II. Sea-jellies (Medusje). 



Class 1. Umbrella-jellies {Ilydroniediisaf). 

 Class 2. Comb-jellies {Ctenophorce). 



Time only can decide which grouping best coiTCSponds 

 to the natural relationships, wdien the genealogy of the 



